D2 speed garage

Dragbike Yunani Style

2013-05-18T13:46:00.001-07:00

Yoshimura Manifold

2013-05-18T13:44:00.001-07:00

Yoshimura carburateur

2013-05-18T13:43:00.001-07:00

engine jupiter

2013-05-18T13:32:00.001-07:00

d2speed

2012-11-07T12:04:00.003-08:00

Supri Indra Paul Afif Dani

Dani Paul Supri Indra Kicli

Paul Dani Indra

Jupiter Ungu

Paul

Honda Supra With Big Valve

2011-04-10T10:27:00.000-07:00

hehehehehe.....watch it........on my honda 1997 bike.....

2011-04-10T10:22:00.001-07:00

Intake Porting Suzuki Smash
take from http://ratmotorsport.wordpress.com

Exhaust Tuning

2011-04-10T10:19:00.000-07:00

1. What is Exhaust Tuning?
When I was fooling around with racing 4-stroke motorcycles a long time back, we used exhaust tuning to increase horsepower by cutting each pipe to a specific length. In order to gain the maximum effect the pipes have to be totally separate from each other, with no common manifold between any of the cylinders. That is not always practical, but it's the ideal. You will notice that on drag racing engines there are always individual pipes sticking out the sides, and those pipes are set to a specific length, which is critical.
We used a formula to determine the length of the exhaust pipe. Because the pressure waves in an exhaust system travel at the speed of sound, we had to know the approximate temperature of the exhaust gases because sound waves move faster in hot air than in cold air. Meaning, it travels further in the same amount of time in a hot gas environment versus a cold gas environment.
Then we calculated how long it would take a sound wave to move from the exhaust valve seat to the end of the pipe and back again. A round trip. Next we needed to know the approximate RPM at which we wanted to run at top end, and then determine how long the exhaust valve would be open from beginning of travel to end of travel.

2. Exhaust Tuning in 4-Stroke Engines; Valve Overlap
When we got it right we would have an exhaust pipe that would carry a positive pressure wave of exhaust pulse down the pipe to the open end. There it would collapse and create a negative pressure wave that would return back up the pipe. If the negative wave arrives back at the exhaust valve just before it closes, it will suck more of the exhaust gases out of the cylinder. This lowers the pressure inside the cylinder and makes the next intake stroke more efficient.
On a 4-stroke, the intake valve begins to open while the exhaust valve is still off it's seat. This is valve overlap. This allows the negative exhaust pulse (the reflection of the positive pulse) to actually pull more fresh mixture past the intake valve and into the cylinder. Here's how it works, and it has nothing to do with exhaust tuning as such.
When the combustion cycle begins, the piston is forced downward; this is the power stroke. Near the bottom of the power stroke the energy is mostly spent and the exhaust valve starts to open. It will actually start to open slightly before bottom dead center. The exhaust charge then begins to rush out the exhaust pipe.
The exhaust gases rushing out are further assisted by the piston pushing up on the exhaust stroke. This forms a stream of hot gas in very rapid motion away from the cylinder. This stream of hot gas has inertia and it will tend to continue moving in the same direction out the exhaust pipe even after the piston stops pushing it. This creates a region of reduced pressure in the vicinity of the exhaust valve.
By opening the intake valve just prior to top dead center, while the exhaust valve is still open (overlap), the gases going out the exhaust pipe will begin pulling the new intake mixture in behind them. Or, the intake stream will try to flow into the region of reduced pressure behind the exhaust stream, if you want to look at it that way. So overlap merely takes advantage of the inertia of the exhaust gases and the low-pressure region that it produces near the exhaust valve at the end of the exhaust stroke.
That part of the overlap design is common to all 4-stroke engines in order to gain additional charging of the cylinder with fuel mix at high RPM. The higher the RPM we design for, the greater the intake and exhaust overlap we build into the cam lobes. Most engines are fitted with exhaust manifolds that collect all the gases from a bank of cylinders. They also usually have a long pipe and muffler. So, while the physics of gases in motion will apply there, tuning for the exhaust pulse will not.

3. Intake Tuning on a 4-Stroke Engine
On the 4-stroke, intake tuning is also a consideration. When the intake valve opens, it creates a negative pressure wave which will travel to the end of the intake pipe. It is reflected as a positive wave which then travels back down the pipe. It will create a sharp, supercharging effect if it can be timed to arrive just before the intake valve closes. That requires individual carb throats to each cylinder though, and no common intake manifold.
The old Dodge Ramchargers used that method in the days when carbs were the standard way to get fuel mixture into an engine, and you could see the eight intake stacks sticking up from the hood. Those intake stacks were cut to a specific length for tuning. The intake tuning was used to "ram" a little more charge into the cylinder just before the intake valve closed; hence the name of that racing team, the Ramchargers.
So you can see the principle involved here and why both intake and exhaust systems are engineered for specific lengths if we want to make use of the pulses within the pipes. Two-strokes use the same principles, but the intake side is not tuned. We can see one undesirable side effect of the intake system on our 2-strokes, however, which is spitting back of some of the fuel mixture at lower rpms.

Woooowwwwww

2011-04-10T10:15:00.001-07:00

Carburator and Fuel System

2011-04-10T10:08:00.001-07:00

How The Intake Tuning Working In Your Car

2011-04-10T10:06:00.001-07:00

The intake system on a four-stroke car engine has one main goal, to get as much air-fuel mixture into the cylinder as possible. One way to help the intake is by tuning the lengths of the pipes.

When the intake valve is open on the engine, air is being sucked into the engine, so the air in the intake runner is moving rapidly toward the cylinder. When the intake valve closes suddenly, this air slams to a stop and stacks up on itself, forming an area of high pressure. This high-pressure wave makes its way up the intake runner away from the cylinder. When it reaches the end of the intake runner, where the runner connects to the intake manifold, the pressure wave bounces back down the intake runner.

If the intake runner is just the right length, that pressure wave will arrive back at the intake valve just as it opens for the next cycle. This extra pressure helps cram more air-fuel mix into the cylinder -- effectively acting like a turbocharger.

The problem with this technique is that it only provides a benefit in a fairly narrow speed range. The pressure wave travels at the speed of sound (which depends on the density of the air) down the intake runner. The speed will vary a little bit depending on the temperature of the air and the speed it is moving, but a good guess for the speed of sound would be 1,300 feet per second (fps). Let's try to get an idea how long the intake runner would have to be to take advantage of this effect.

Let's say the engine is running at 5,000 rpm. The intake valve opens once every two revolutions (720 degrees), but let's say they stay open for 250 degrees. That means that there are 470 degrees between when the intake valve closes and when it opens again. At 5,000 rpm it will take the engine 0.012 seconds to turn one revolution, and 470 degrees is about 1.31 revolutions, so it takes 0.0156 seconds between when the valve closes and when it opens again. At 1,300 fps multiplied by 0.0156 seconds, the pressure wave would travel about 20 feet. But, since must go up the intake runner and then come back, the intake runner would only have to be half this length or about 10 feet.

Two things become apparent after doing this calculation:

1. The tuning of the intake runner will only have an effect in a fairly narrow RPM range. If we redo the calculation at 3,000 rpm, the length calculated would be completely different.
2. Ten feet is too long. You can't fit pipes that long under the hood of a car very easily.

There is not too much that can be done about the first problem. A tuned intake has its main benefit in a very narrow speed range. But there is a way to shorten the intake runners and still get some benefit from the pressure wave. If we shorten the intake runner length by a factor of four, making it 2.5 feet, the pressure wave will travel up and down the pipe four times before the intake valve opens again. But it still arrives at the valve at the right time.

There are a lot of intricacies and tricks to intake systems. For instance, it is beneficial to have the intake air moving as fast as possible into the cylinders. This increases the turbulence and mixes the fuel with the air better. One way to increase the air velocity is to use a smaller diameter intake runner. Since roughly the same volume of air enters the cylinder each cycle, if you pump that air through a smaller diameter pipe it will have to go faster.

The downside to using smaller diameter intake runners is that at high engine speeds when lots of air is going through the pipes, the restriction from the smaller diameter may inhibit airflow. So for the large airflows at higher speeds it is better to have large diameter pipes. Some carmakers attempt to get the best of both worlds by using dual intake runners for each cylinder -- one with a small diameter and one with a large diameter. They use a butterfly valve to close off the large diameter runner at lower engine speeds where the narrow runner can help performance. Then the valve opens up at higher engine speeds to reduce the intake restriction, increasing the top end power output.

KOREK HARIAN MATIC

2011-04-10T10:04:00.001-07:00

Belakangan ini banyak mekanik merancang mesin balap skubek atau skutik.

Bahkan kabar bagusnya, tahun depan ada 4 seri lagi. Untuk itu sebagai persiapan perlu teori yang pas supaya ada panduan dan tidak salah langkah.

Paling menarik untuk dicermati kelas 150 cc. Di Yamaha Mio harus menggunakan piston 57 mm. Sedang stroke standar Mio y…aitu 57,9 mm. Bagaimana menentukan ukuran klep dan karburator yang digunakan?

Dan kita panggilkan Ibnu Sambodo yang begawan 4-tak Indonesia untuk berbagi ilmu. Menurut pria yang tinggal di Sleman, Jogja ini sebagai permulaan katanya harus menentukan letak power di rpm berapa. Jadi, bukannya menentukan besarnya klep dulu.

Ibnu mengambil contoh motor balap di tim Manual Tech. Peak power sekitar di 13.000 rpm untuk kelas 110 cc. Rata-rata tim lain bermain di 12.000 rpm. Biar gampang ditentukan di 12.000 rpm saja ya, maklum di skubek yang transmisi otomatis belum ada batasan. Juga karakter tenaga bagusnya di gasingan bawah.

Juga mesti tahu dulu gas speed (GS) di lubang porting. Menurut referensi dari tuner luar negeri 80 meter/detik. Untuk motor balap Ibnu, yaitu 100-105 meter/detik. Angka ini menentukan homogenitas campuran bensin-udara. Jika kelewat gede atau kurang dari 80 m/detik akan tidak homogen. Lebih gampang 100 m/detik saja ya.

Selanjutnya mencari ukuran diameter inlet port. Menurut mekanik beken disapa Pakde itu, paling gampang bisa diukur dari diameter lubang inlet di kepala silinder yang ketemu dengan intake manifold. Untuk menentukan besarnya bisa lihat rumus:

Diameter Piston2

Gas Speed= ————————–x Piston Speed

Diameter Inlet Port2

Piston Speed = (2 x stroke x rpm)/60.

Yamaha Mio punya stroke 57,9 mm (0,0579 meter). Pada gasingan 12.000 rpm, maka Piston Speed = (2 x 0,0579 x 12.000)/60 = 23,16 meter/detik. Nah, dari sini bisa menghitung diameter inletnya. Yaitu:

Diameter Piston²

Diameter Inlet Port = √————————–x Piston Speed

Gas speed

0,057²

Diameter Inlet Port = √—————– x 23,16

100

Diameter Inlet Port = 0,0274 meter = 27,4 m

Nah, dari sana ketahuan bahwa diameter inlet port 27,4. Dari sini memang rada rumit jika mau tahu ukuran diemeter klep ideal. “Harus melalui rumus yang panjang dan perlu riset lama. Terutama tahu dulu diagram kerja kem dan bikin pusing,” jelas Ibnu yang sarjana elektro sekaligus mesin itu.

Diameter klep tergantung letak peak power yang dimau

Untuk itu Ibnu mau kasih rumus ringan. Katanya diameter inlet port itu untuk ukuran motor cc kecil, yaitu 0,85 x diameter klep isap. Maka diameter klep isap = Diameter Inlet Port/0,85 = 27,4/0,85 = 32 mm.

Klep buang lebih kecil lagi. Besarnya berkisar 0,77 sampai dengan 0,80 x diameter klep isap. Jika diambil yang paling besar yaitu 0,80 x 32 = 25,6 mm. Nah, ini dirasa sangat gede jika klep isap 32 mm dan buang 26,6 mm. Rasanya seperti sangat susah dipasang pada kepala silinder yang hanya menggunakan piston diaemeter 57 mm.

Tapi rumus ini jika peak power kepingin berada di 12.000 rpm. Untuk ukuran matik harusnya lebih rendah lagi. Kan transmisi otomatis (CVT) butuh tenaga galak di putaran bawah supaya cepat melesat.

Jika tenaga bermain di gasingan 11.000 rpm klep isap 30,6 mm dan klep buang 24,5 mm. Kalau mau lebih rendah lagi misalnya di 10.000 rpm, maka klep isap 29,5 dan buang 23,6 atau 24 mm. Jadi, besarnya diameter klep tergantung dari letak peak power yang dimau.

Venturi Karbu

Menentukan besarnya venturi karburator juga bisa berpatokan dari perbandingan. Sebagai contoh diambil dari buku panduan flowbench merek Superflow SF-110/120. Perbandingannya 0,85 x diameter klep.

Sebagai contoh seperti di atas jika diameter klep isap 32 mm. Maka venturi karburator 32 x 0,85 = 27 mm. Namun dirasa susah mencari karburator ukuran 27 mm. Kalau mau lebih gampang, pilih aja yang 28 mm. Seperti Keihin PWK 28 misalnya.

Artikel diatas, ditulis cara menentukan besarnya diameter lubang intake atau isap di skubek. Contohnya di Yamaha Mio. Tentunya harus ditentukan dulu letak peak power di rpm berapa yang dimau.

Batang klep. Pilih yang sama dengan punya Mio biar gesekan ringan

Letak peak power atau tenaga puncak yang dimau akan menentukan besarnya diameter lubang isap. Juga akan menentukan pemilihan diameter payung klep dan ukuran karburator yang diterapkan.

Rupanya cara itu lumayan menarik perhatian skubeker yang doyang ngebut. Seperti Nugroho dari Surabaya. “Jika sudah tahu ukuran payung klep yang dipakai, kira-kira pakai punya klep apa dan gimana pasangnya?” tanya pemakai Yamaha Nouvo itu lewat SMS.

Untuk Yamaha Mio yang mau turun di kelas 150 cc pakai piston 57 mm, bisa menggunakan klep beberapa tingkatan. “Tergantung letak peak power ada di rpm berapa,” timpal Ibnu Sambodo, begawan 4-tak yang minggu lalu memberikan rumusnya.

(1) Klep Sonic
Misalnya menyesuaikan dengan klep yang tersedia di pasaran. Sebagai contoh klep Honda Sonic in 28 mm dan ex 24 mm. Herganya berkisar dari Rp 150 ribu sampai Rp 200 ribu. Namun risikonya harus potong batang klep lantaran kepanjangan. Kalau tidak repot comot aja merek TK, TDR atau Daytona khusus untuk Mio.

Klep ukuran 28/24 ini banyak dipakai skubeker. Jika menggunakan rumus yang diberikan Ibnu minggu lalu, karakter tenaga atau peak power berkisar di 9.000 rpm. Namun pakai klep ini harus menggeser posisi sudut klep di kepala silinder.

Untuk itu Chandra dari bengkel bubut Master Tjendana Bandung kasih panduan. Menurut Chandra, standar Mio klep in kemiringan dari vertikal 31,5 derajat dan klep buang 35,5 derajat. Jika memakai klep Sonic, kemiringan harus dibikin lebih landai supaya tidak saling bertabrakan.

Dari perhitungan menggunakan rumus sinus dan cosinus, didapat klep isap kemiringannya harus dibikin 29,1 derajat. “Klep buangnya 33,5 derajat dengan memperhitungkan jarak antar klep 4 mm,” jelas Chandra langsung dari Jl. Pagarsih, No. 146, Bandung.

Pasang klep lebar. Kemiringan klep harus diatur ulang di tukang bubut

Jarak antar klep bagusnya 3-4 mm supaya mesin adem

(2) Klep EE 31/25,5 mm

Pilihan kedua, jika tenaga mesin mau berada di kisaran 11.000 rpm. “Bisa pakai klep berlogo EE yang diameter payung klep isap 31 dan buang 25,5 mm,” jelas Mariasan Kocek dari JP Racing di Ciputat, Tangerang.

Jangan lupa jarak antar klep diseting 4 mm dan sudut kemiringan klep isap 28 derajat dan buang 33 derajat. Karakter klep EE antijeber alias tidak mengembang meski menggunakan per yang keras dan kem lift tinggi.

Klep ini memang batangnya lebih panjang. Konsekuensinya harus main potong supaya ukurannya sama dengan punya Mio. Namun kelebihannya diameter batang klep kecil alias sama dengan punya Yamaha Mio. Sehingga gesekan lebih ringan.

Meski harus main potong batang, namun harganya lumayan ringan. Katanya sih pihak JP Racing menjualnya dengan banderol Rp 150 ribu.

(3) Klep GL Pro Platina

Pilihan lain bisa coba klep GL-Pro platina alias tipe lama. Diameter payung klep in 31,5 mm dan ex 26 mm. Dipastikan cocok untuk mengejar tenaga di gasingan 11.500 rpm. Harganya lumayan bersahabat. Seperti buatan Indoparts yang dilego kisaran Rp 70 ribu.

Untuk pemasangan klep ini Chandra yang spesialis ubah klep itu kasih bocoran. “Kemiringan klep isap dipasang 27,5 derajat, sedang kemiringan klep buang 32,5 derajat, kondisi ini jarak antar klep biar aman 5 mm,” jelas Chandra.

Namun menggunakan klep GL-Pro meski murah ada konsekuensinya. Batang harus dipotong lantaran kepanjangan. Juga diameter batang klep lumayan gede, yaitu 5,5 mm. Bandingkan punya Mio asli hanya 5 mm.

Jarak Antar Klep

Jarak antar klep memang tergantung dari kem. Terutama overlap dan lift. “Namun jangan kelewat jauh mematok jarak antar katup isap dan buang. Bagusnya sih 3 sampai 4 mm,” jelas Jesi Lingga Siwanto dari JP Racing.

Dari analisis Jesi, jika jarak antar klep 5 mm atau lebih akan berakibat mesin panas. Biasanya leher knalpot membara. Menandakan temperatur mesin tinggi.

Namun kalau digunakan untuk keperluan racing, tetap perlu modifikasi di beberapa bagian. Juga perlu perlakuan khusus. Apalagi klep yang dipakai asalnya dari motor atau mobil harian. Tujuannya agar didapat flow atau aliran gas bakar bagus.

Paling awal bisa dilihat pada batang klep yang kepanjangan. Ini terjadi jika menerapkan klep Honda Sonic atau CS-1, GL-Pro platina dan merek EE keluaran JP Racing. Untuk itu harus dipotong disesuaikan panjang klep Mio.

Perlu diketahui, panjang standar klep Mio 65 mm. “Untuk itu, ukuran panjang klep CS-1, Sonic, GL-Pro dan EE dibikin sepanjang 65 atau 66 mm juga,” ucap Chandra Sopandi yang tukang bubut Master Tjendana itu.

Untuk memotong, gunakan mesin bubut supaya presisi. Trus diikuti dengan membuat alur untuk dudukan kuku klep (gbr. 1). Fungsi kuku klep untuk mengunci klep bareng per katup. “Alur ini posisinya 2,5 mm dari ujung batang klep,” jelas Chandra yang masih lajang itu.

Dalam membuat alur untuk kuku klep harus dibikin radius. “Lebar alur dibikin 2 mm dan radius 1 mm. Maka dalam radius hanya tinggal 0,5 mm,” jelas Chandra yang masih jomblo itu?

Rada repot kalau pakai klep GL-Pro, meski murah harus kerja dua kali. Pertama, kudu memotong klep yang kepanjangan. Kedua, kudu ngecilin diameter batang klep. Batang klep yang dikecilin pada ujungnya sejauh 8 mm. Diameter batang klep asalnya 5,5 mm dibikin 5 mm. Selanjutnya tinggal bikin alur untuk kuku klep. Hasilnya bisa lihat (gbr. 2).

Untuk membentuk batang klep EE, proses kerjanya sama dengan di klep Sonic. Kan diameter batang klep EE sama dengan punya asli Mio yang 5 mm.

gbr.1

gbr.2

Proses Hardening

Setelah klep dipotong, tentunya wajib kembali dibikin keras. Tujuannya supaya batang klep tidak jeber dipukul rocker-arm. Untuk itu, butuh proses hardening. Tekniknya batang klep dipanaskan menggunakan las asitilen. Jangan menggunakan las karbit karena dikhawatirkan kurang panas.

Perlu juga diwaspadai saat proses hardening. Jangan kelewat panas yang berisiko klep jadi patah. Sebaliknya, kalau kurang panas juga bakal lembek alias masih mudah jeber. Proses pemanasan cukup sampai membara kira-kira mendekati titik leleh besi.

Gampang kok caranya mengetahui sudah mendekati titik leleh. Perhatikan warna ketika klep dibakar. Awalnya klep akan merah membara, kemudian oranye dan begitu mencapai kelir kuning stop pemanasan.

Begitu klep berwana kuning segera celup pada cairan kimia. Cairan kimia ini campuran dari RBK (Racun Besi Kuning) atau RBM (Racun Besi Merah) dengan air. Komposisinya 100 cc air dicampur dua sendok makan RBK atau RBM. Terserah mau pakai RBK atau RBM, menurut Chandra sama saja.

“Untuk mendapatkan RBM atau RBK, bisa cari di toko kimia. Kemasan ½ kg Rp 100 ribu,” jelas Chandra dari Jl. Pagarsih, No. 146, Bandung.

Brother berkacamata itu juga kasih penjelasan. Katanya dalam proses pemanasan tidak bisa menggunakan campuran RBK plus air. Ada klep yang cukup pakai oli. Bedanya bisa langsung dites menggunakan magnet.

Magnet ditempelkan pada batang klep. Jika bersifat magnetik, klep nempel di magnet. Artinya, setelah proses hardening cukup dicelup oli. Seperti klep Sonic, batang atas nempel dan bawah enggak, maka cukup dicelup oli.

Jika seperti klep EE dan GL-Pro berlainan. Klep isap bersifat magnetik, setelah pemanasan dicelup oli doang. Klep buangnya yang non magnetik alias tidak nempel magnet harus menggunakan cairan RBK dan air.

Informasi lebih komplet seputar proses hardening, bisa konsultasi langsung sama Chandra. Brother yang sedang mendambakan kekasih ini bisa ditanya di (022) 70600396.

Radius klep

OTOMOTIFNET – Ibnu Sambodo yang begawan 4-tak masih percaya klep standar yang asli pabrik. Seperti klep Sonic yang dipakai untuk road race. Katanya punya material lebih terjamin kekutannya dibanding yang aftermarket dengan spek yang belum jelas dan tidak tahu buatan mana.

Namun digunakan untuk keperluan balap, klep standar harus dimodifikasi. Minimal dari bentuknya. Namun jika batangnya dipotong, tetap harus dihardening atau diperkeras supaya kuat. Seperti ditulis minggu lalu.

Kali ini Ibnu kasih tahu modifikasi dari ukuran. Pertama ukuran pada bagian pertemuan antara payung dengan batang klep. “Bagian ini membentuk radius atau sudut,” jelas Ibnu yang asli wong Jowo itu.

Untuk klep racing biasanya dibuat enteng. Maka pada bagian radius atau leher ini dibuat tipis. “Tapi kendalanya flow atau aliran gas bakar rada berkurang karena membentuk lekukan yang tajam,” jelas Ibnu yang kini mulai tinggal di Jakarta mengurus tim Kawasaki.

Diakui juga oleh pria beken disapa Pakde ini. Katanya membentuk bagian ini rada susah, tukang bubut juga belum tentu presisi. “Makanya untuk sementara banyak dilupakan atau dikira-kira dulu,” jelas mekanik yang berpenampilan sederhana ini.

Untuk keperluan balap, sementara sebagai patokan, Ibnu kasih radius 1/3 dari diameter payung klep. Sebagai contoh klep isap 28 mm, jika dikalikan 1/3 hasilnya 9,3 mm.

Jika merunut dari buku Four-Stroke Performance Tuning karangan A. Graham Bell, sedikit berbeda. Untuk ruang bakar hemi chamber dengan klep miring, besarnya 0,24-0,26 dari diameter payung klep. Andaikan 0,26 x 28 mm hasilnya radius leher klep 7,28 mm.

Menurut Ibnu, ini bukan rumus. Hanya sebagai perbandingan. Apalagi riset yang dilakukan oleh Graham Bell dilakukan di mobil. Mesin mobil dan motor berbeda putaran. Untuk motor balap bergasing sampai 14.000 rpm, sedang di mobil hanya separuhnya.

Perlu dipertimbangkan dalam menggunakan perbandingan Ibnu atau Graham. Radius yang kelewat gede atau kecil ada pengaruh terhadap flow dan berat klep. Jika lekukan atau radius kecil tidak tajam tapi bagus untuk flow. Tapi klep jadi berat.

Berbeda jika leher klep dibikin dengan radius besar. Dari sisi bobot memang enteng, tapi terdapat lekukan yang tajam. Bikin flow jadi berkurang, untuk itu harus tetap mempertimbangkan dua faktor ini.

Perkecil batang hanya sampai ujung bos klep

Batang Diperkecil

Untuk memperbesar flow, batang klep juga harus dimodifikasi. Terutama batang klep yang berada di lubang atau port isap dan buang. Batang klep yang kebesaran lumayan menghambat aliran gas bakar.

Pada klep bebek yang hanya 5 mm, oleh Ibnu Sambodo hanya dibikin 4,5 mm. Bagian ini dari radius klep sampai bagian yang menyentuh tepat dibibir bos klep. Jangan kelewat dalam yang berakibat sedikitnya kontak antara batang klep dengan bosnya. Jadinya cepat oblak.

Bahkan menurut Ibnu lagi, sebenarnya bisa saja batang klep dari radius atau leher sampai bibir bos klep dibikin 4 mm. Namun risikonya ketahanan jadi berkurang. Tapi aliran gas bakar lebih lancar.

Sudut 45 ketemu sitting klep, sudut 30 untuk flow Sudut 45 Dan 30 Derajat

Kedua sudut di bibir payung klep ini belum lama ditulis oleh MOTOR Plus tepatnya edisi 507. Fungsinya untuk memperlancar flow gas bakar. Sekadar mengingatkan, sudut 45 derajat paling bawah dan di atasnya 30 derajat.

Dua sudut ini harus dibentuk menggunakan reface valve. Nantinya sudut yang 45 derajat akan bersentuhan dengan sitting klep di kepala silinder. Sedang yang 30 derajat untuk mempermudah aliran gas bakar.

Dibuat Cekung

Untuk memperingan bobot klep, masih ada cara yang bisa ditempuh. Caranya dengan membuat tipis payung klep. Namun jangan terlalu tipis yang bisa berakibat klep gampang pecah. Bagian yang bisa dibuang daging pada tengah payung klep, caranya dibuat cekung.

Payung klep cekung seperti di katup Sonic atau CS-1. Meski cekung namun tidak terlalu dalam yang berakibat kompresi turun. Tapi, bagian yang cekung di tengah ini dirasa tidak mengurangi kekuatan klep. Sebab masih tebal lantaran di belakangnya masih ada batang klep.

Ibnu bilang, bagian paling luar klep memang lebih kuat dibanding dalam. Untuk itu, ketika mengikis klep jangan terlalu dalam. Katanya bisa mengurangi kekuatan dari klep itu sendiri

JETTING CARBURETOR

2011-04-10T10:02:00.001-07:00

Jetting is the process of making adjustments to the air and fuel jet sizes in order to fine tune the carburetion to suit the load demands on the engine and make the power delivery consistent and optimum. Too much anxiety is placed on jetting. Most people just want to call me on the phone and ask what jets they should put in their carb. That’s an impossible question because that the big dirt bike magazines attempt to answer just to increase readership. People get confused because they read jetting specs in a magazine, put those jets in their bike and seize the engine. Any quoted jetting in this book is just a baseline. Most magazines don’t list parameters for their jetting specs like; Brand new bike running with VP C-12 fuel with Silkolene oil mixed at 30:1 and a NGK 8 spark plug, ridden by a really slow lard-ass editor twisting the throttle on a hard-packed track. Some part numbers and jet sizes are given in the Tuning Tips section for models that definitely need certain jets in order to get the bike near the baseline. There is an old saying that says you can fish for a man and feed him for a day or teach him to fish and enable him to feed himself for life. Here is a quick lesson on how to jet your dirt bike.

The Differences in Two-Stroke and Four-Stroke Carbs

2011-04-10T10:01:00.000-07:00

The difference between a two-stroke and four-stroke engine is intake velocity. Two-stroke engines have lower velocity so the needle jet has a half-moon shaped hood protruding into the venturi to produce a low pressure area that aids in drawing the fuel up through the needle jet. Four-stroke carbs need to atomize the fuel more so than a two-stroke carb because so much of the fuel shears along the intake port and separates from the mixture stream. Four-stroke carbs have more jets and finer adjustment screws, plus they usually are equipped with an accelerator pump. A typical state of the art four-stroke carb is the Keihin CR.
The latest trend in two-stroke carbs features a pump that sprays fuel into the venturi from 1/4th to 3/4th throttles. In the past, carb manufacturers made jet needles that attempted to compensate for the natural lean condition of the mid-range but that compromised the jetting at full throttle. The auxiliary pumps are powered by electricity supplied by the alternator (about 5 watts) and controlled by either a throttle position or an rpm sensor.

Identification Guide to Popular Carb Types

Keihin PWK Carburetor.

On two-stroke engines, several different model carbs have been used over the years, but there are basically two big carb manufacturers. Kehin and Mikuni are two popular brands of Japanese carbs used on nearly every dirt bike.
Kehin has several different models. The most popular ones are the PJ, PWK, and PWM. The PJ is used on Honda CR125, 250, and 500 models from 1985-1997 The slide is oval shaped and there are no additional pumps, and it’s just a simple carb. In fact it’s so simple that the choke and idle screw share the same jet. The PWK was the next step up from the PJ. The PWK has a crescent shaped slide and a separate idle circuit from the choke. The PWK is used on Kawasaki KX125, 250, and 500 models from 1990-97. The latest version of the PWK features a pump to supply extra fuel in the mid-range. The PWM is similar to the older PWK (no pump) and the overall length is shorter.
Mikuni has several different model carbs too. The original model VM had a round slide. There are many different parts available including needle jets of different diameters and jet needles with different taper angles and diameters. The next model was the TMX, which became available in 1987. It was a flat-slide carb, which offered a greater peak flow rate. The TMX was revised several times, becoming smaller with fewer parts. The TMS carb introduced in 1992 had no main or pilot jet. The slide and jet needle handled all the jetting. That carb worked great on 250cc bikes but never became popular. The PM is the latest Mikuni model. It features an oval crescent shaped slide and a very short body. That carb comes standard on Yamaha YZ125 and 250 1998 and newer models.
Carburetor Parts and Function
A carburetor is a device that enables fuel to mix with air in a precise ratio while being throttled over a wide range. Jets are calibrated orifices that take the form of parts such as pilot/slow jets, pilot air screw, throttle valve/slide, jet needle, needle jet/spray-bar, air jet, and main jet. Fuel jets have matching air jets, and these jets are available in many sizes to fine-tune the air-fuel mixture to the optimum ratio for a two-stroke engine, which is 12.5: 1.
Fuel Jets, Air Jets, and Throttle Positions
Three circuits control the air: the air-screw, the throttle slide, and the air jet. Four circuits control the fuel: the pilot/slow jet, the spray-bar/needle jet, the jet needle, and the main jet. The different air and fuel circuits affect the carb jetting for the different throttle-opening positions, as follows:
Closed to 1/8 throttle—air screw and pilot/slow jet
1/8 to 1/4 throttle—air-screw, pilot/slow jet, and throttle slide
1/4 to 1/2 throttle—throttle slide and jet needle
1/2 to full open—jet needle, spray-bar/needle jet, main jet, and air jet
(Note: On many modern carbs the spray-bar/needle jet and air jets are fixed-diameter passages in the carburetor body and cannot be altered.)

cylinder head porting suzuki F150

2011-04-07T16:03:00.000-07:00

workbench d2

2011-03-30T15:17:00.000-07:00

Inlet Porting

2011-03-07T10:05:00.001-08:00

This is a decription about inlet porting

CHASIS TIPS 1

2011-03-07T09:58:00.001-08:00

CHASSIS TIPS:
Stock Car Q&A with Michael Leone

QUESTION: When shortening the rear upper trailing arms
to change the pinion angle, it seems to bind up the
upper arms due to their shortened length. They seem to
need to be pinched together more in order to have the
correct angles and movement. Any thoughts and
suggestions would be helpful.

ANSWER: Moving the holes does create some bind, no easy
way around it, but there are some things that you can
do that will help.

First of all you can't go too far, maybe an inch or two
max. When you drill the holes, do them with the arms in
the car, at proper ride height (on blocks), with the
correct tires and stagger (no springs). Rock the rear
housing forward to the angle you want, then drill the
holes through the bushing. You will have to run the
bolts a little loose to prevent bind. Weld big washers
on each side to prevent the loose bolt from wearing the
hole into a slot. You can also use upper arms out of a
late 60's chevelle, they are shorter from the factory.
I always preferred shortening the stock ones though,
that way you can line the holes up right. We used to
check for proper bolt tightness by putting the car in
gear (or park) and rocking the car forward and back.
look at the rear arms through the trunk, if the bolts
are too loose, you'll see it. Make sure that every
bushing/frame/mount surface is smooth and lubricated
with anti-seize. Make sure that the spring pockets are
flat after you change the pinion angle.

ENGINE TIPS

2011-03-07T09:56:00.001-08:00

ENGINE TIPS:
"5 tips for shaving ET this weekend - Part 1"
By Don Terrill
taken from http://racingsecret.com

1.) More RPM - I've found that it's just about
impossible to have too much (higher number) gear in
your car if your goal is the lowest ETs. Just keep
adding gear ratio until you stop gaining ET, even if
the MPH falls off. Remember: racing is usually ET not
MPH.

2.) Jetting - If I had to guess I'd say that 80% of all
race engines are jetted too rich. Some of the signs of
a rich setting are an engine that misses or surges. Try
jetting down two sizes and see what happens. Learning
how to read spark plugs is my best advice.

3.) Ignition Timing - Go up or down two degrees and
make a test. I've seen engines tuned with just a couple
of degrees too much timing lose 30hp, so don't think
you can't have too much.

4.) Oil - If you aren't using synthetic oil already,
try it, it's worked every time for me. The other big
thing is oil level, on a wet sump engine too much oil
is a killer. No engine needs more than 6gts, no matter
what the pan manufacture says. In fact; too much oil is
bad.

5.) Shift Points - If you're going to miss your shift
point, miss it early. A late shift is an ET killer,
especially in the lower gears. Here's a test: If you
seem to really be knocked back into the seat after the
shift, you're late. The Reason? Your body went forward
before the shift because of lack of acceleration.

For info on how to read spark plugs:
http://racingsecrets.com/spark_plug_reading.shtml

ADVANCED TWO-STROKE TUNED EXHAUST SYSTEM by John Perkins Jay Robichaud Brian Ellis

2010-11-27T03:58:00.000-08:00

The Society of Automotive Engineers
Clean Snowmobile Challenge 2002
(SAE CSC 2002) is an engineering
design competition for college and
university student members of the
Society of Automotive Engineers (SAE).
The intent of the competition is to
provide universities with an
intercollegiate competition that allows
them to re-design stock snowmobiles to
reduce emissions and noise, while
maintaining or improving the
performance of the snowmobile. The
emphasis is on low-cost modifications
that are suitable for implementation in
rental sleds. The modified snowmobiles
are expected to be quiet, emit
significantly less unburned hydrocarbons
and carbon monoxide than conventional
snowmobiles (without significantly
increasing oxides of nitrogen emissions),
and maintain or improve the
performance characteristics of
conventional snowmobiles.

OBJECTIVES
The primary goal is to prepare an
existing 2-stroke sled for the
competition. This sled is fuel-injected
and has the ability to be designed for
good mixture control. This project
attempts to tune the exhaust system on
the sled while accommodating the use of
an air injection pump. One of the
primary problems with a 2-stroke engine
is the use of an air-fuel mixture to
scavenge the cylinder. The resulting
exhaust contains a lot of unburned
hydrocarbons.

AVAILABLE RESOURCES
! A 462.8cc Ski-Doo snowmobile
! A snowmobile Dynojet
dynamometer
! 5 gas emissions analyzer
! An installed fuel-injection
system
! Basic tools
! Machine shop
! Composites fabrication
! Design and Simulation of 2-
Stroke Engines simulation
software by Gordon P. Blair
*NOTE: the software is virtually
useless, as it models a 125ccGP
motorcycle with drastic differences
from the Ski-Doo engine. Computer
software can help you with the design,
but don’t expect super design from the
software. The software uses
mathematical formulas that are
approximations of reality, and the
software made for home-computers
uses even more simplified formulas
because good simulation of expansion
chambers requires much more
computer-power than your home-PC
can offer. (5)
! SRW Team baffle-cone
calculator Excel file to size, cut
and construct the exhaust shapes
correctly
! Daqbook DBK19 Thermocouple
card
! Omega Engineering, Inc.
Precision Fine Wire
Thermocouples (Type K&E)

THE 2-STROKE ENGINE CYCLE
The characteristic feature of the twostroke
engine is its means of operation.
In a two-stroke engine, every stroke
leaving top dead center is an expansion
stroke (i.e., a working stroke). In a four
stroke engine, there is only one working
stroke against three negative strokes
(induction, compression, and discharge).
Two-stroke engines are found in small
devices such as chain saws, dirt bikes,
and snowmobiles because they have 3
important advantages over four-stroke
engines:
• Two-stroke engines dont have
valves, which simplifies their
construction and lowers their
weight.
• Two-stroke engines fire once every
revolution (four-stroke engines fire
once every other revolution) this
gives the two-stroke engine a
significant power boost.
• Two-stroke engines can work in
any orientation, which can be
important in something like a
chainsaw. A standard four-stroke
engine may have problems with oil
flow unless it is upright, and
solving this problem can add
complexity to the engine.
These advantages make two-stroke
engines lighter, simpler and less
expensive to manufacture. Two-stroke
engines also have the potential to pack
about twice the power into the same
space because there are twice as many
power strokes per revolution. The
combination of light weight and twice
the power potential gives two-stroke
engines a great power-to-weight ratio
compared to many four-stroke engine
designs.
You don’t normally see two-stroke
engines in cars, however. That’s because
two-stroke engines have a couple of
significant disadvantages that will make
more sense once we look at how it
operates. (1)
You can understand a two-stroke engine
by watching each part of the cycle. Start
with the point where the spark plug fires.
Fuel and air in the cylinder have been
compressed, and when the spark plug
fires the mixture ignites. The resulting
explosion drives the piston downward.
Note that as the piston moves
downward, it is compressing the air/fuel
mixture in the crankcase. As the piston
approaches the bottom of its stroke, the
exhaust port is uncovered. The pressure
in the cylinder drives most of the
exhaust gases out of cylinder, as shown
here:
As the piston finally bottoms out, the
intake port is uncovered. The piston’s
movement has pressurized the mixture in
the crankcase, so it rushes into the
cylinder, displacing the remaining
exhaust gases and filling the cylinder
with a fresh charge of fuel, as shown
here:
Note that in many two-stroke engines
that use a cross-flow design, the piston is
shaped so that the incoming fuel mixture
doesn’t simply flow right over the top of
the piston and out the exhaust port.
Now the momentum in the crankshaft
starts driving the piston back toward the
spark plug for the compression stroke.
As the air/fuel mixture in the piston is
compressed, a vacuum is created in the
crankcase. This vacuum opens the reed
valve and sucks air/fuel/oil in from the
carburetor. *Our engine lacks a reed
valve and is fuel injected, not carbureted.
Once the piston makes it to the end of
the compression stroke, the spark plug
fires again to repeat the cycle. It is
called a two-stoke engine because there
is a compression stroke and then a
combustion stroke. In a four-stroke
engine, there are separate intake,
compression, combustion and exhaust
strokes. (1)
You can see that the piston is really
doing three different things in a twostroke
engine:
• On one side of the piston is the
combustion chamber, where the
piston is compressing the air/fuel
mixture and capturing the energy
released by the ignition of the
fuel.
• On the other side of the piston is
the crankcase, where the piston is
creating a vacuum to suck in
air/fuel from the carburetor (ours
is fuel-injected) through the reed
valve and then pressurizing the
crankcase so that air/fuel is
forced into the combustion
chamber.
• Meanwhile, the sides of the
piston are acting like valves,
covering and uncovering the
intake and exhaust ports drilled
into the side of the cylinder wall.
Because the piston alone is doing so
many different things, two-stroke
engines are simple and lightweight.
You must also mix special two-stroke oil
in with the gasoline. In a four-stroke
engine, the crankcase is completely
separate from the combustion chamber,
so you can fill the crankcase with heavy
oil to lubricate the crankshaft bearings,
located on either end of the piston’s
connecting rod and the cylinder wall. In
a two-stroke engine, on the other hand,
the crankcase is serving as a
pressurization chamber to force air/fuel
into the cylinder, so it can’t hold a thick
oil. Instead, you must mix oil in with the
gas to lubricate the crankshaft,
connecting rod and cylinder walls. If you
do not mix in the oil, the engine won’t
last very long. (1)

DISADVANTAGES OF THE 2-
STROKE
• Two-stroke engines don’t last
nearly as long as four-stroke
engines. The lack of a dedicated
lubrication system means that the
parts of a two-stroke engine wear
out a lot faster.
• Two-stroke oil is expensive, and
you need about 4 ounces of it per
gallon of gas. You would burn
about a gallon of oil every 1,000
miles if you used a two-stroke
engine in a car.
• Two-stroke engines do not use
fuel efficiently, so you would get
fewer miles per gallon.
• Two-stroke engines produce a lot
of pollution -- so much, in fact,
that it is speculated that you
won’t see them around too much
longer.
Two-stroke engine pollution comes from
two primary sources. The first is the
combustion of the oil. The oil makes all
two-stroke engines smoky to some
extent, and a badly worn two-stroke
engine can emit huge clouds of oily
smoke. The second reason is that each
time a new charge of air/fuel is loaded
into the combustion chamber, part of it
leaks out through the exhaust port. That’s
why you see a sheen of oil around any
two-stroke boat motor. The emitted
hydrocarbons from the fresh fuel,
combined with the leaking oil is an
obvious hazard to the environment.
These disadvantages mean that twostroke
engines are used generally in
applications where the motor is not used
very often and a fantastic power-toweight
ratio is important. (1)

THE TUNED PIPE
In the 1950’s, an engineer by the name of
Walter Kaadan was consulted by
motorcycle racers, asking him to help
them squeeze more power and speed out
of their motorcycles. After some
experimentation, he found that the 2-
stroke engines in motorcycles were
affected by its exhaust characteristics.
He found that by varying the length of
straight exhaust pipes, the performance
also changed accordingly. After further
experimentation, he found that a
divergent cone instead of a straight pipe
worked better, and this heralded the
arrival of the 2-stroke tuned pipe.
The basic principle of the tuned pipe is
making use of the moving air masses in
the exhaust to assist in the scavenging
(the process whereby the exhaust gases
are removed and replaced with un-burnt
mixture) of a 2-stroke engine. (2)
The exhaust pipe of a two-stroke engine
attempts to harness the energy of the
pressure waves from combustion. The
diameter and length of the five main
sections of a pipe are critical to
producing the desired power band. The
five sections of the pipe are the head
pipe, diffuser cone (divergent), dwell or
belly, baffle cone (convergent), and the
stinger. In general, after market exhaust
pipes shift the power band up the RPM
scale. Most pipes are designed for
original cylinders not tuned cylinders.
(3)
Changing the exhaust pipes on your twostroke
snowmobile can have a marked
effect on the engine’s power
characteristics. Simply put, it’s because
the two-stroke exhaust system,
commonly referred to as an expansion
chamber, uses pressure waves
emanating from the combustion chamber
to effectively supercharge your
cylinder.(6)
Each time the exhaust port of a 2-stroke
cylinder is uncovered, exhaust gases
rush out of the opening and through the
exhaust pipe.
This causes a high pressure wave to
radiate out of the pipe towards the
exhaust opening. However, the
momentum of this moving mass of air
also creates a low pressure wave that
follows behind it. If this is carefully
timed, this low pressure wave can be
used to suck in the fresh fuel/air mixture
from the transfer ports.
The pressure wave has now been
reflected at the end of the chamber, and
perfectly timed pushes all fresh mixture
back into the cylinder just as the piston
closes the exhaust-port.
This process repeats itself at the same
frequency at which the engine is running
and thus, if the exhaust pipe can be made
to resonate at the operating RPM of the
engine, this will improve the engine’s
efficiency. It must be noted that at a low
(lower than the resonant frequency)
RPM range, this low pressure pulse
would return too soon, bouncing back
out the exhaust port. The converse is true
for an RPM range higher than the pipe’s
resonant frequency, whereby the low
pressure pulse returns too late such that
the exhaust port is closed. (2) & (5)
An engine’s exhaust port can be thought
of as a sound generator. Each time the
piston uncovers the exhaust port (which
is cut into the side of the cylinder in twostrokes),
the pulse of exhaust gases
rushing out the port creates a positive
pressure wave which radiates from the
exhaust port. The sound will be the same
frequency as the engine is turning, that
is, an engine turning at 8000 RPM
generates an exhaust sound at 8000 RPM
or 133 cycles a second--hence, an
expansion chamber’s total length is
decided by the RPM the engine will
reach, not displacement. (6)
The speed of these waves is more or less
constant, though it’s affected slightly by
the temperature of the air. Higher
temperatures mean that the air molecules
have more energy and move faster, so
sound waves move faster when the air is
warmer.
A complicating factor is that changes in
the shape of the tube cause reflections,
or changes, in the sound waves: Where
the section of the tube grows in
diameter, there will be sound waves
reflected back towards the start of the
tube. These waves will be the opposite
of the original waves that they reflected
from, so they will also be negative
pressure waves. Therefore, by gradually
increasing the diameter of the tube, a
gradual, more useful negative wave can
be generated to help scavenge, or pull
spent gasses out of, the cylinder. (6)
Putting a divergent cone on the end of a
straight pipe lengthens the returning
wave, broadening the power band and
creates a rudimentary expansion
chamber.
To sum up, when the negative wave
reaches the exhaust port at the correct
time, it will pull some of the exhaust
gases out the cylinder, helping the
engine to scavenge its spent exhaust gas.
And putting a divergent cone at the end
of the straight (parallel) "head" pipe
broadens the returning wave. The
returning negative wave isn’t as strong,
but it is longer, so it is more likely to
find the exhaust port open and be able to
pull out the exhaust gases. As with plain,
straight pipes, the total length of the pipe
with a divergent cone welded on
determines the timing of the return
pulses and therefore the engine speed at
which they are effective. The divergent
cone’s critical dimensions are where it
starts (the distance from the exhaust port
to the start of the divergent cone is called
the "head" pipe), while the length of the
megaphone and the rate at which it
diverges from the straight pipe
determine the intensity and length of the
returning wave--A short pipe which
diverges at a sharp angle from the head
pipe gives a stronger, more straight-pipelike
pulse. Conversely, a long, gradual
divergent cone creates a smaller pulse of
longer duration. In addition, the
negative wave is also strong enough to
help pull fresh mixture up through the
transfer ports. (6)
While adding a divergent cone to the
head pipe produces great tuning
advantages, it has its limitations as well:
The broader negative wave from a
megaphone can still arrive too early and
pull fresh mixture out of the cylinder.
However, putting another cone, reversed
to be convergent, on the end of the first
divergent pipe will reflect positive
waves back up the pipe. These positive
waves will follow the negative waves
back to the exhaust port, and if properly
timed will stuff the fresh mixture that
was pulled into the pipe back into the
exhaust port right as the piston closes the
port. (6)
In addition to head pipe length,
divergent and convergent cone lengths,
an expansion chamber has three more
crucial dimensions. The length of the
straight ’belly’ between the divergent and
the convergent cones, the length of the
tailpiece ’stinger’ and the diameter of the
belly section. The stinger acts as a
pressure bleed, allowing pressure to
escape from the pipe. Back pressure in
the pipe, caused by a smaller-diameter or
longer stinger section, helps the wave
action of the pipe, and can increase the
engine’s performance. This, presumably,
happens since the greater pressure
creates a more dense, uniform medium
for the waves to act on--waves travel
better through dense, consistent
mediums. For instance, you can hear a
train from a long way away by putting
you ear to the steel railroad track, which
is much denser and more uniform than
air. But it also causes the engine to run
hotter, usually a very bad characteristic
in two-strokes. (6)
The length of the belly section
determines the relative timing between
the negative and positive waves. The
timing of the waves is determined by the
length of this characteristically straight
pipe. If the belly section is too short,
positive waves have a shorter distance to
travel, and return to the exhaust port
sooner. This is good if the engine is
running at a higher speed, bad if you
want to ride on the street. The diameter
of the belly section is crucial for one
simple reason: ground clearance. It’s
hard to keep big, fat pipes off the
ground, though V-Fours have solved that
for now since two of the pipes exit
directly out the back. (6)
A complete two-stroke pipe has a
properly tuned header, convergent, belly,
divergent and stinger sections--a difficult
process to mesh successfully.
Modern pipes generally have a gently
divergent head pipe to keep gas velocity
high near the port, a second cone of
"medium" divergence, and a third
divergent cone with a strong taper. A
belly section connects to multi-angled
convergent cones, which should exit in a
straight line into the stinger for good
power. As you can see, modern twostroke
expansion chambers create a
complex scenario and are quite difficult
to tune.(6)
To start with, you need a good design of
the chambers you are about to make.
This is absolutely the most important
thing to get a good result. What a good
design is, obviously depends upon what
kind of power you want, what tune you
want the rest of the engine have, etc.
There are many factors that decide how
the chambers should be designed, for
example if you raise the exhaust port,
you will move the powerband to higher
rpm’s, and by lengthening the chambers
you will move the powerband to lower
rpm’s. A good chamber will give lots of
power over a wide rpm-range. A poorly
designed chamber will have a weak
pressure wave that won’t suck the charge
out of the cylinder, and in turn won’t
push much fresh charge back into the
cylinder, producing less horsepower,
wasting fuel and increasing pollution.(5)
Here are a few examples of possible
chamber designs:
or possibly,
THE TUNED PIPE DESIGN
PROCESS
As previously stated, expansion
chambers are shaped as they are so they
reflect sound waves back at the exhaust
port to hold the burnable charge in the
cylinder. Without the expansion
chamber, a large amount of power
producing fuel and air would escape
from the exhaust port because the
exhaust port must be open when the
fresh fuel/air charge rushes into the
combustion chamber. Four-strokes don’t
need two stroke type expansion
chambers because they have valves that
seal their exhaust ports during the intake
cycle. Though each section of an
expansion chamber has its own areas of
influence on power delivery, it is
important to point that no section of an
expansion chamber works entirely
independent of the others. Any change
in length, shape or volume in any part of
the pipe will bring about changes in the
way the pipe affects performance.
Generally, changes that hurt
performance in one area will boost
performance in another, but it is possible
to make changes that only hurt or help
performance.(4)

EXPANSION CHAMBER
COMPONENTS
HEADPIPE: Tapered head pipes are
relatively more difficult and costly to
manufacture, so they are rare on nonrace
machines. Tapered head pipes have
proven to boost performance and ease
pipe tuning in their main area of
influence low to mid rpm power
which has proven to be best for most
racing applications. In general, a
relatively longer head pipe will bring
about more bottom-end power at the
expense of peak power. A short head
pipe generally brings on stronger peak
power and subtracts bottom-end.
CONES: The length, volume and taper
of the first cone strongly influence the
amount of peak power the engine will
produce. A relatively short, steeply
tapered, first cone, creates high peak
power with sacrifices at other engine
speeds. Pipes on Open-class bikes
usually have gradually tapered first
cones because smoothness, rather than
peak power, is of more benefit.
BELLY: A pipe’s midsection is where
length or volume adjustments are made
to compensate for less than "ideal" head
pipe, first cone, final cone and
stinger/silencer dimensions that can’t be
used due to the size and shape of the
bike or snowmobile. The pipe’s
midsection or "belly" can be enlarged,
shortened or lengthened to bring about
the same results as most "ideal" designs.
FINAL CONE: What happens after an
engine’s power peaks is nearly as
important as the peak itself. Controlling
power after the peak, the overrev or
overrun is the final cone’s job. A
relatively longer, gently tapered final
cone will give you more overrev. A
short, steep final cone gives you less.
Why not go for lots of overrev? You
will lose too much top-end. It’s pretty
much all give and take thats where the
engineering comes in.
STINGER: The tailpipe, or stinger, is
as important as any part of the pipe. Its
size and length influences peak power
and bottom-end, and can even affect an
engine’s resistance to holing pistons.
In general, smaller stinger diameters
create more peak horsepower but
increase the likelihood of melted pistons
because they bottle up the exhaust
heat. Big stinger diameters boost
bottom-end at the expense of peak
power. Excessively large stinger
diameters can hurt performance at all
engine speeds due to insufficient back
pressure. Stingers length is important,
too, because it’s part of the total pipe
length and volume. Generally, longer
stingers help low and midrange power.
Why not run a long, large diameter
stinger? The pipe has to fit on the
bike.(4)
EXHAUST TUNING THEORY
The two-stroke engine can be considered
atmospheric when the cylinder filling
(scavenging) is superimposed to the
exhaust phase, i.e., with the exhaust port
opened to the external atmosphere. The
effectiveness of the cylinder filling with
fresh charge depends on small
differences of pressure, and the twostroke
engine can only tolerate small
amounts of exhaust back pressure.
In SI engines, which use the crankcase
as a scavenging pump, the dynamic
effect plays a fundamental role in filling
the cylinder with fresh charge. As
explained earlier, every time the exhaust
flow meets a section increase, a negative
pressure is generated and propagates in
the opposite direction of flow with the
speed of sound. On the other hand, if
the flow finds a restricted section, a
positive pressure wave always
propagates in the opposite direction with
the speed of sound. (8)
According to acoustic theory, the
propagation of waves depends strictly on
the length and section of ducts, volumes,
and logically on the speed of sound.
Therefore, the exact tuning for the
required boost effect is possible only for
a particular range which is usually at the
BMEP condition (brake mean effective
pressure). A tradeoff between maximum
obtainable BMEP and range width is
possible, and different solutions can be
used, depending on the required engine
output. One parameter is fundamental:
the propagation of sonic speed waves.
The speed of sound depends on several
parameters, however if the medium in
which the sound wave propagates is the
same, the most important term is the
absolute temperature as follows:
a = √kRT
or approximately
a = 20√T (m/sec)
Predicting exhaust gas temperature is
difficult because an exact calculation
must be taken into account which
includes the heat transmission from the
exhaust system to the ambient and the
operating air-fuel ratio of the engine. In
Figure 1 below, the reference
temperature into the exhaust system is
reported versus engine maximum power
RPM, and thus a zone corresponding to
the specific output of the appropriate
engine can be defined to assist with
empirical data.
Figure 1
(8)
SHARP RANGE TUNING
With high-performance engines, such as
snowmobiles, the maximum tuning
effects need to be obtained. Therefore,
the dynamic effect of compression and
expansion waves must be carefully
managed. In this case, calculations can
be performed following a method of
solving the differential equations
representing the physics of the actual
engine. Sometimes, an empirical
technique can be used to quickly check
the geometrical dimensions. Using
Figure 2 below with the following
labels, we start with:
Figure 2
S = Total exhaust angle (CA deg)
T = Total scavenge angle (CA deg)
D1 = Exhaust duct internal diameter (m)
N = tuning (RPM)
A negative reflection is requested after
(S-T)/2 = A (CA deg)
The time for the reflection is
tr = A/6N
The value of the sonic speed can be
estimated, if the temperature inside the
muffler is known, as
c1 = 20√T1 (m/sec)
where T1 is the absolute temperature in
ºK. Thus,
2Lcol = c1 tr
Lcol = c1 tr /2
Divergent Part (angle 8º)
D2 = √(6(D1
2))
Ld = (D2 D1)/ tg 4º
Convergent Part (angle 15º)
A positive reflection (compression
wave) is needed afterward
A + T = B (CA deg)
With similar considerations, using a new
value for c2 if the temperature is
changed (C2 = 20√(T2):
tc = B / 6N
Ltot = c2tc / 2
Lc = (D2 Du) / 2 tg 7.5º
Lct = D2 / 2 tg 7.5º
Ltot = Lcol + Ld + Lcil +Lct / 2 + s
Thus the length of the cylindrical part
can be derived as:
Lcil = Ltot s Lcol Ld Lct / 2
The tail has an approximate length of
Ltail = 12Du
*************************(8)
ENGINE MODELING AND
SIMULATION TECHNIQUES
One-Dimensional Methods
The purpose of 1-D methods is to
calculate the response of the different
parts of the engine- namely, the inlet,
crankcase, scavenge and exhaust ducts,
and muffler to determine, by using
calculations on the entire flow through
the engine, the predicted performance
and the final value of different
parameters such as charging efficiency,
short-circuit ratio, and noise pressure
levels. Usually this method consists of
splitting the engine into several smaller
parts that then can be schematized with
ducts of different sections and lengths
and connecting volumes.
The basic equations can include heat
transfer and friction in the ducts, but
obviously cant take into account the
turbulence effect in any part of the
engine. These methods have the
advantage of a rapid response on overall
engine performance, making it easy to
compare the influence on engine output
of different geometrical configurations.
The general drawback lies in the fact
that accurate external calibrations,
derived from experimental tests, are
necessary, and then its important to
have a solid knowledge of the physical
behavior of every engine family. The
valid use is only to obtain comparative
results for a well-defined class of
engines.
Many methods have been developed for
solving differential equations. These
range from the characteristic method,
which could also be solved graphically,
to modern numerical methods made
possible only by the advent of
computers. One of the most effective
known methods, particularly dedicated
to the two-stroke engine, is the Two-
Stroke Simulation Program developed
by Queens University of Belfast (QUB).
This method includes friction, heat
transfer, and multiple ducts, as well as
catalyst insertion and multi-cylinder
capabilities.
The 3 conservation equations are:
continuity, momentum (without
friction), and constant entropy.
The continuity equation is
∂(ρu) / ∂x = −∂ρ / ∂t
The momentum equation is
− ∂ρ / ∂x = ∂Du / Dt
Where Du/Dt is the substantive
derivative of velocity with respect to
time.
Du / Dt = ∂u / ∂t + u∂u / ∂x
The expansion of the continuity and
momentum equations, respectively,
yields
p x u t u u x
and
p t u u x
∂ ∂ + ∂ ∂ + ∂ ∂
∂ ∂ ∂ + + ∂ ∂ =
1/ ( / ) / /
1/ ( / ) / / 0
ρ
ρ
The sonic speed at the pressure p and
density ρ and entropy is given by
a2 = (∂p / ∂ρ )s
for an ideal gas
a2 = (kp /ρ )
The 3rd conservation condition
(isentropic flow) is
/ = ( / )2k /(k+1)
ref A p p a a
when pref and aA are reference values.
After substitution, the continuity
equation can be expressed in terms of a
and u as
2 /(k −1)a∂a / ∂u + ∂u / ∂t + u∂u / ∂x = 0
and the momentum equation can be
expressed as
2 /(k −1)a∂a / ∂u + ∂u / ∂t + u∂u / ∂x = 0
After some lengthy manipulation of
these equations, the following equation
can be obtained:
da/dt + (k-1) / 2du / dt = 0 (*)
on a line on the x-t field (where x is the
current abscissa) whose slope is
dx / dt = u + a
and
da /dt – (k-1) = 2du /dt (#)
on a line whose slope is dx /dt = u -a
To generalize the results, its useful to
write the equations in non-dimensional
form, introducing
A = a/aA; U = u/aA; X = x/L; and
Z = aAt/L
As Riemann variables.
Consider the line of slope dX/dZ = U+A
shown in the Figure 3.
Figure 3
This is known as a position
characteristic and is seen to be in the
direction of a disturbance propagating
toward the right through the gas in the
pipe.
Integrating EQN (*)
A + (k-1) / 2U = constant = λ
The constant λ exists at any point along
the position characteristic. A and U can
vary only along a position characteristic
within the restraint imposed by the
relation in this equation.
Therefore, if the properties of the initial
disturbances are known, a family of λ
lines can be drawn, shown in Figure 4.
Figure 4
Disturbances moving toward the left will
propagate along a line of slope dX/dZ =
U A. Similarly, EQN(#) above gives:
A – (k-1) / 2U = constant = β
The value of β is derived from the initial
values of A and U. These lines are also
shown in Figure 3.
The terms β and λ are known as
Riemann variables. The particle
velocities and fluid properties can be
found at any point of the X-Z plane:
(1+b)/2 = A = a/aA
(1-b)/2 = U = u/aA
Because
a/aA=(p/pref)(k-1)/2k
That is,
((1+b)/2)2k/(k-1) = p/pref
((1+b)/2)2 = T/Tref
((1+b)/2)2/(k-1) = r/rref
The results for the last 6 equations can
be used to produce a numerical solution
to problems of unsteady flow.
Obviously, the real problem is more
complicated, i.e., the duct may have a
variable or a sonic shock wave may be
generated.
Two-Dimensional Methods
Theoretical three-zone model for loopscavenge
engines:
The mathematical model consists of five
conservation laws in somewhat 3-D
form:
( ( / )) / 0
( ( / )) /
( ) / ( ) / ( ) /
∂ Γ ∂ ∂ ∂ + =
− ∂ Γ ∂ ∂ ∂ −
∂ ∂ + ∂ ∂ + ∂ ∂
ψ ψ
ψ
ψ
ψ
ρψ ρψ ρψ
x y S
x x
t u x u y
Any of the five equations can be derived,
where the symbols have the following
significance:
x and y designate the Cartesian
coordinates of a Eulerian frame
Ψ is the general transport property
ΓΨ is the transport coefficient
SΨ is the source term
u and v are the velocity components in
the x and y directions
t designates the time
ρ is the density
μ is the viscosity
k designates the thermal conductivity
cp is the heat capacity
h is the specific stagnation enthalpy
p is the pressure
Dab is the mass diffusion coefficient
X designates the mass fraction of the
fresh charge
The differential equations must be
modified to allow the domain of the
solution to be always within the
boundary of the volume occupied by its
gas with a coordinated transformation.
The cylinder domain is divided into
three zones shown in Figure 5.
Figure 5
For Zone 3, the mesh is confined
through DD and CC. During the
period in which the ports are closed, the
zone collapses to a line. Zone 2 is
bonded by CC (inlet port closure line)
and BB (exhaust port closure line).
This zone also collapses to a line when
both inlet and exhaust ports are closed.
Zone 1 is bonded by BBand the
cylinder head AA. This zone contracts
and expands only in the compression and
expansion periods, respectively.
The transformation replaces the
coordinate system (x,y,t) with (x, yt, t)
when the non-dimensional coordinate yt
varies in each zone between 0 and 1.
The final equations are solved with the
finite difference method through a grid.
The results provide a means of
evaluating not only the overall
scavenging efficiency, but also of
mapping the scavenging process versus
crank angle. The results for a loopscavenged
engine appear in good
agreement with the experimental data,
shown in Figure 6.
Figure 6
Figure 7 and Table 1 below show the
comparison of calculated vs.
experimental data for scavenging
profiles.
Figure 7
Table 1
Three-Dimensional Methods
KIVA is the most recent of a long series
of fluid-dynamics codes devoted to the
study of engine applications and
developed at Los Alamos National
Laboratory since the early 1970s.
KIVA solves the transient 2-D and 3-D
chemically reactive fluid flows with
sprays. It is applicable to laminar or
turbulent flows, subsonic or supersonic,
and single-phase or two-phase flows.
The gas phase solution procedure is
based on a finite volume method called
the Arbitrary Lagrangian-Eulerian
(ALE) method. The grid is a single
block structure. KIVA can simulate
two-stroke engines, allowing connecting
and disconnecting of port volumes with
in-cylinder volume. This is performed
automatically, also controlling the timestep
when opening of the ports results in
a sudden (sonic) acceleration of the
flow. To move the piston from its top
dead center position to bottom dead
center position and back again, a special
piston motion logic has been devised.
The logic is called snapper. As shown
in Figure 8, the lowest plane of active
cylinder coincides with the piston crown
and with the piston velocity.
Figure 8
All other vertices remain stationary.
Periodically, however, a new plane of
piston crown vertices replaces the old
one and assumes its role of following the
piston motion. The old plane of piston
vertices is snapped back to its original
position, which is now below the piston
crown, and a simple remap onto the new
mesh (redefining cells, vertex, and flags)
is performed. When the piston is
moving downward, the procedure is
reversed. The experimental results
derived from a loop-scavenged twostroke
engine show very good agreement
with predicted velocity field and a
coherent evaluation of two-stroke
characteristic parameters.
(8)
EMISSIONS
BASIC PRINCIPLES
The main source of the generation of
unburned hydrocarbon emissions in SI
(spark ignition) engines is caused by the
short-circuit of the fresh mixture through
the exhaust port during the scavenging
phase. The meaning of the short-circuit
is that part of the incoming fresh mixture
after the inlet in the cylinder is shortcircuited
directly through the exhaust
port. Although the emissions of carbon
monoxide (CO) and nitrogen oxides
(NOx) depend mainly on the combustion
characteristics, unburned hydrocarbon
(HC) emissions in SI engines are caused
by this short-circuit of fresh mixture
through the exhaust port.(8)
BASIC SOLUTION
One of the methods used in production
to reduce hydrocarbon and CO
emissions is air injection into the exhaust
system. Oxides of nitrogen will not
necessarily be reduced; in fact they may
be increased if sufficiently high exhaust
temperature results from the combustion
of the CO and hydrocarbons with the
added air or if the injected air enters the
cylinder during the overlap period,
thereby leaning the mixture in the
cylinder. To achieve a high degree of
exhaust system oxidation of HC and CO,
a high exhaust temperature coupled with
sufficient O2 and residence time to
complete the combustion is needed. If a
flame is established, the heat generated
by the combustion of the CO and
hydrocarbons keeps the reaction
going.(7)
Because of its abundance, the carbon
monoxide in the exhaust provides most
of the combustion-generated heat. The
basic factors governing the combustion
of CO and HC in the exhaust system are:
composition of the reacting mixture,
temperature and pressure of the mixture,
and residence time of the mixture or
time available for reaction.(7)
General laboratory testing has shown
that the minimum HC concentrations
occurred at rich mixtures. When too
much air was injected, especially at lean
mixtures, excessive cooling of the
exhaust increased HC concentrations to
levels above those with no air. Thus, the
normal oxidation process was apparently
inhibited by this cooling. The effect of
air injection on CO concentrations was
somewhat different. Exhaust CO was
uniformly low at most rich-air-fuel
ratios. A small increase in CO occurred
slightly richer than stoichiometric. At
stoichiometric and leaner, CO was very
low. The leanest air-fuel ratio for best
emission reduction was 13.5:1.
Normally, engine operation at such a
rich mixture would reduce fuel economy
by 10%. The very low emissions with
rich mixtures and air injection arose
from a fire in the exhaust system. For
mixtures leaner than the small CO peak
in Figure 9, non-luminous oxidation
occurred and CO emission reduction was
relatively poor.
Figure 9 (7)
OPTIMIZATION OF AIR INJECTION
RATE
At each air-fuel ratio there exists one
minimum air injection rate that provides
maximum emission reduction. Minimum
air flow is desired in order to reduce
pump power requirement, size and cost.
Air injection is not highly effective in
reducing CO emission unless a luminous
burning flame occurs.(7)
EXHAUST TEMPERATURE AND
PRESSURE
Exhaust system insulation is necessary
to achieve high reaction rates in engines
with well-cooled exhaust ports.
Insulation also helps to reduce emissions
during warm-up by accelerating the
warm-up rate.
At mixtures significantly leaner than
stoichiometric (in the range of 16 to
17.5:1) air injection is not needed to
supply O2; in fact it would only cool the
exhaust to too low a temperature for any
reaction to occur. On the other hand, at
such lean mixtures only extremely good
heat conservation can produce
temperatures high enough for
appreciable reaction.
For lean mixtures, the following
equation for the concentration of
hydrocarbons leaving the exhaust system
was derived:
where
K T W
C C KrO P V
i  


 
 −
= 2
3
2
2
0 exp
Co = conc. of HC leaving exhaust
system
Ci = conc. of HC leaving
cylinders and entering exhaust system
Kr = specific reaction rate,
ft3/lbm*mole/sec
K3 = constant
O2 = oxygen concentration in
exhaust gases, volume %
P = exhaust pressure (psia)
V = exhaust system volume
available for reaction, ft3
T = absolute temperature, °R
W = mass flow rate of air, lb/sec.
Note the importance of the pressure
term. Increasing exhaust back pressure
promotes after-reaction. However,
commercially, the possible back pressure
increase is small. General laboratory
results show that a decrease in exhaust
temperatures from 1100°F to 1000°F
decreases the reaction rate by a factor of
10 Something to think about.(7)
EXHAUST SYSTEM VOLUMERESIDENCE
TIME EFFECTS
Reactor volume may be viewed as the
volume of the exhaust system which is
insulated and at the high temperature
needed for reaction. General laboratory
testing shows that if the exhaust
temperature were at 1400°F (Ski-Doo
specs show 1330°F), only twice the
convention system volume is required
for virtually complete elimination of the
hydrocarbons. On the other hand, if the
temperature were only 1200°F, eight
times the volume would achieve only a
76% reduction.
Increasing the exhaust system volume
increases the residence time during
which reactions can occur. This will be
a benefit only if the added surface area
does not result in excessive cooling.
Thus, when large volume exhaust
manifolds are used, they must be well
insulated. In conclusion, increasing the
residence time of the exhaust by
increasing volume improves both the CO
and HC oxidation effectiveness of air
injection and reduces the injected air
flow requirement provided that good
heat conservation is maintained. Note:
this applies to both rich and lean fuel
mixtures. The most effective reactors are
those that run rich with air injection.
Rich engine operation produces low NO
and high CO and H2 emissions. Vehicle
experience shows that combustion of the
CO and H2 with the injection air
generates temperatures high enough to
oxidize virtually all the unburned
hydrocarbons.(7)
Table 2 below shows the stock exhaust
emission values taken with the engine
idling at 129°F.
HC CO CO2 O2 NOx
5690ppm 1.81% 3.7% 0 14.1%
Table 2
OUR DESIGN PROCESS
When Jay, Brian and I initially started
the design process, we planned on
quickly throwing together a pipe and
then being able to focus the majority of
our attention on decreasing harmful
emissions. NOT EVEN CLOSE. First
and foremost, we realized the need to
have more than just a general idea of
two-stroke engine operation in order to
understand exactly where these so-called
emissions were coming from. During
the process of engine research, we
quickly found just how much of an
effect the exhaust system has on optimal
operation of the two-stroke engine: a
huge one. This realization immediately
altered our design project to something
of much larger scale than we had
originally anticipated. Now we had to
first successfully design a high
performance pipe for this two-stroke
snowmobile (obviously no easy task in
itself) with emissions still in mind of
course, and then deal with the emissions
issues. So
We decided to look for suitable twostroke
engine simulation software where
we would be able to take engine and
exhaust characteristic values of the Ski-
Doo sled and plug them into the
program, generating values we had
already achieved on the Dyno (values of
horsepower, rpm etc). This would give
us a baseline where we would simply be
able to change the dimensions of the
exhaust (within the simulation program)
and see how it affected our engine
performance, therefore allowing us to
optimize the design by changing values
accordingly. Didnt happen. Below is a
table of the current engine values.
Feature Dimensions/Ratios
Bore 69.5mm
Stroke 61mm
Total Displacement 462.8cc
Con rod length 130mm
Crankcase
Compression ratio
1.55
Squish Clearance .58mm
Wrist pin-to-crown 25
Wrist pin-to-skirt 25
Wrist pin offset 0
Fly wheel diameter 243mm
No. of exhaust ports 1
Top corner radius 10mm
Bottom corner radius 10
No. of transfer ports 5
Ave max. width 19mm
Top corner radius 6.8mm
Bottom corner radius 6.8mm
Fuel type Gasoline
Air : Fuel ratio 13.5
Table 3 – Note: Values are metric for
compatibility w/ software
We found a simulation program by
Gordon Blair (see Proff. Mick Peterson
for instruction manual) and it was
disastrous. It is not user friendly,
requires much more engine characteristic
values than other simulation software on
the market, is written to simulate a single
cylinder GP motorcycle, and
incorporates the use of a reed valve
(which the sled does not have). Most of
these details were not apparent by
reading the available literature. We
worked around the single cylinder
issue by doubling the rpms, but when
trying to deal with the reed valve, or lack
thereof, we hit a wall. You cant just set
the reed valve values to zero or it throws
the entire program off. Not only was it
useless, more importantly, we wasted
valuable time.
At this point wed already flushed $500
of the Universitys money down the
toilet on inapplicable software, so new
software was out of the question. But if
you want make an omlet, you gotta
break a few eggs, right? The only thing
left to do was establish the stock exhaust
temperature gradient using
thermocouples and Daqbook, then
design the new exhaust empirically
(hand calcs and 1,2,3,-Dimensional
analysis as shown above and in lab
notebook), fine-tuning with a trial-anderror
process. We already had stock
horsepower, torque vs. rpm curves
(Appendix A), as well as temperature
profiles (Appendix C) so we could
calculate lengths and diameters from
earlier equations and estimate sizes
based upon where we wanted to see
improvements made.
GETTING STARTED
Because a long, gradual divergent cone
creates a smaller pulse of longer
duration, we manipulated the
calculations to allow for a divergent
cone that was longer and more gradual
than the existing one. This alteration
also strengthens the negative wave
enough to help pull fresh mixture
through the engine transfer ports. This is
how we were able to reach maximum
horsepower shortly after the track was
engaged.
As stated above, if the belly section is
too short, positive waves have a shorter
distance to travel, and return to the
exhaust port sooner. This is good if the
engine is running at a higher speed, bad
if you want to ride on the street. Because
a snowmobile operates at such high
rpms, this is the type of design we went
after. Our first test pipe had a belly
length approximately 3 longer than the
stock belly. We started longer because a
pipe’s midsection is where length or
volume adjustments are made to
compensate for less than "ideal" head
pipe, first cone, final cone and
stinger/silencer dimensions that can’t be
used due to the size and shape of the
sled. The pipe’s midsection or "belly"
can be enlarged, shortened or lengthened
to bring about the same results as most
"ideal" designs. Its much easier to
change a length, cut and weld, than it is
to change multiple lengths and
diameters.
Our convergent (final) cone was made
shorter and steeper than the stock
exhaust to give less overrev, in turn
preserving top-end. Top-end is crucial
to successful snowmobile operation.
A stinger similar to stock diameter was
used to sustain sufficient back pressure
to maintain the wave action of the pipe,
and hopefully maintain the engine’s
performance. Because smaller stinger
diameters deliver more peak
horsepower, but also increase the
likelihood of melted pistons (because of
bottling up the exhaust heat), we opted
to use an approximate stock diameter
and adjust the belly length to increase
performance. A larger stinger diameter
was out of the question because it may
boost bottom end, but only at the
expense of peak power. Stinger length is
also important to help low and midrange
power. This is why we made ours
longer than stockit worked. Below in
Table 4 and Figure 10 you can see the
dimensions of our first prototype.
L1
L2
D1 D2
D2
7.13°
Head Pipe
Head Pipe Convergent Cone
and stinger
Divergent Cone
& Belly
Divergent Cone &Belly
L3 L4
D2
D3
8°
Figure(s) 10
D1 2.78
D2 2.39
D3 5.81
Du 1.25
L1 1.575
L2 6.89
L3 12.17
L4 13.54
L5 8.51
L6 15.00
Table 4
MATERIAL SELECTION
We employed carbon steel sheet metal,
.0312 thick. The primary reason(s) for
the selection of this material are its
commonplace in the motorcycle
industry, its ability to be easily welded
and it is lighter than the stock exhaust.
Stainless steel was found to be more
brittle and therefore more susceptible to
cracking over repeated seasons of use.
METHOD TO THE MADNESS
The SRW Team in Italy was kind
enough to email us their Excel file
calculating arc and cone lengths needed
in order to roll the exhaust up correctly.
We then drew out the flat shapes on
carbon steel sheetmetal and hired
Downeast Sheetmetal in Brewer to roll
and weld. It is crucial that the exhaust is
as close to being perfectly round as
possible for correct flow and wave
propagation. Figure 11 below shows the
process of drawing the correct arcs and
cone lengths on the sheetmetal.
Figure 11
Hiring Downeast Sheetmetal for
welding/rolling future exhaust projects is
highly recommended. They are not only
familiar with the exhaust and do
excellent work, but had an average
turnover time of less than 24hrs. Figure
12 shows the 1st of six Prototype exhaust
pipes built before Note the bend in the
head pipe. Because it is at such a sharp
angle, a substantial amount of power
was lost. The local Mieneke dealer was
able to give us another head pipe, at
nearly exact dimensions, with a gentler
curve.
Convergent Cone & Stinger
L5 L6
D3
Du Du
15°
Figure 12
Shown here in Figure 13 is the Daqbook
DBK19 Thermocouple card with type K
& E thermocouples connected to it.
(Instructions for connection and
operation can be seen in Appendix B)
Figure 13
Figures 14 & 15 show the exhaust-end
connections for the thermocouples, held
in with screws, for the Dynojet testing
procedure. This is the apparatus used to
record both stock and new exhaust
temperature profiles.
Stock Thermocouple Connections
Figure 14
Prototype Thermocouple Connections
Figure 15
When testing either of the exhausts,
stock or new, it is important to note that
a separate radiator should be hooked to
the snowmobile cooling system. This
enables sufficient engine cooling while
allowing the engine and exhaust gases to
heat to normal operating levels. We
used a large radiator in a bucket of water
or snow during Dynojet testing. Figures
16 and 17 show the set-up.
Figure 16
You can see that the external radiator is
simply piped into the snowmobiles
cooling system.
Figure 17
After dynojet testing 6 pipes with belly
lengths of 13.54,11.54, 9.54, 8.54, 7
1/8,6 1/8, we found that a 7 1/8 belly
provided optimal results. When
comparing this particular prototype (5th
pipe) with the stock exhaust (Appendix
A) we not only exceeded the maximum
torque provided by the stock pipe, but
also produced virtually identical peak
horsepower. More importantly though,
we sustained 10 horsepower more (at
the track) from ~27mph to 52mph AND
hit peak horsepower almost 1000rpm
sooner, boosting low-end as well.
Note: All Dyno numbers provided in
the Appendix are taken at the track. General
experience shows an approximate loss of ½ the
horsepower provided by the engine in the track.
Appendix A shows all significant test
pipe horsepower/torque curves.
Table 5 shows the pipe dimensions for
optimal power and torque output
(Prototype 5).
D1 2.78
D2 2.39
D3 5.81
Du 1.25
L1 1.575
L2 5.67
L3 12.17
L4 7 1/8
L5 8.51
L6 15.00
Table 5
ANOTHER PITFALL
Once we decided upon which prototype
to use, we returned to Downeast
Sheetmetal and asked them to bend it
up so we could put it on the sled.
Using a basic Cartesian (X-Y-Z)
coordinate system, we provided them
with guidelines, dimensions and
locations for fabrication. Unfortunately,
they soon told us that it was impossible
to construct a divergent cone that would
swing through the angle necessary to fit
under the cowling for them anyway.
We knew there had to be a way to make
the needed cone bend correctly,
maintaining centerline length and end
diameters. We referred back to the SRW
race file and incorporated basic
trigonometry with occasional estimation.
We found the best way to do this was by
constructing a cardboard model to be
used as a welding template, shown in
Figures 18 and 19.
Figure 18
Figure 19
Once the cardboard model was
complete, we made sure it would fit in
the area under the cowling (Figure 20)
and brought it back to Downeast
Sheetmetal to be welded.
Figure 20
The result is shown in Figures 21, 22
and 23.
Figure 21
Figure 22
Figure 23
Now we had to find a way to bend the
stinger because there is no company in
the greater Bangor area that is able to do
it. Its difficult to find a material that
will bend through such a tight angle
without splitting or crimping, and local
shops had no equipment for the job
either.
FABRICATION PROBLEMS
Fortunately, our exhaust pipe design
proved better than the Ski-doo pipe, but
due to a lack of resources and materials,
there was no way to fabricate it
correctly.
In order to arrive at a stinger that would
bend through such a sharp angle, two
common, plumbing sink pipes were
welded together (courtesy of Home
Depot). Because of area and dimension
restrictions the stinger was not welded in
a direct line with the convergent cone.
As stated above, in order to maintain
good power, the convergent cone should
exit in a straight line into the stinger.
In order for the exhaust pipe to reach the
muffler location, the head pipe and the
belly were also lengthened by 2 and 1
respectively.
Appendix A shows the drastic effects
of these design changes upon
performance.
Note: For future groups picking up where we
left off, be sure and use the same convergent and
divergent cones and shorten the belly by one
inch. The optimal head pipe and stinger
dimensions are given in Table 5, so you only
have to find away to make them bend correctly.
PROPOSED IDEA FOR EMISSIONS
REDUCTION
In theory, if you add the right amount of
air to the exhaust gases AND keep this
mixture above a certain temperature
(through good insulation), it will
combust inside the exhaust pipe, burning
off the majority of the harmful
emissions. In theory.
As said above, if too much air is added
you will actually cool the exhaust, in
turn increasing HC emissions.
So if we were going to even come close
to making this happen, we wouldnt be
able to just dump cold air anywhere in
the exhaust flow. We decided to run
3/8 copper tubing (good heat transfer
coefficient) down one side of the exhaust
and back up the other (under the
insulating wrap), to then inject (pointing
downstream) as close to the headers as
possible. This would allow for the air to
pre-heat before it was mixed with the
hottest exhaust gases possible.
AIR PUMP
Finding a suitable air pump is actually a
fairly difficult task; the general market is
quite limited. In order to withstand the
pressure waves created by the exhaust
during operation, a linear piston pump
(positive displacement) is necessary.
The difficulty comes in finding a
variable displacement pump as the sled
will obviously not be running at constant
rpm and therefore, a constant
displacement pump would only suffice
for a very specific rpm value. The only
pump we were able to find that could
withstand exhaust pressures was rated
for 18psi, 2.5ft3 and 12V. It is not
variable displacement and so you can
only hope for a small window for
combustion (if at all). This air pump
accounts for a 2-4% addition to
volumetric flow. Either way, even if it
doesnt burn, your emission numbers
will still decrease because of dilution.
By the way, this is cheating.
However, when the air pump was turned
on during the dyno runs, the temperature
at each point rose 100°F (see Appendix
C ) immediately. This proves that the air
actually ignited, helping to decrease our
harmful emissions.
EMISSIONS RESULTS
All emissions were recorded at an
engine temperature of 129°F. Table 6
shows the emissions recorded with our
fitted pipe with insulation and the air
pump.
HC CO CO2 O2 NOx
1760ppm .65% 1.5% 0 18%
Table 6
HC reduction 70%
CO reduction 64%
CO2 reduction 60%
NOx increase 27%
MUFFLER
The after-market muffler we chose is
from Precision Performance Products. It
is a "Superlite" performance muffler.
After seemingly endless searches on the
internet and dead-ends at dealers, this
was the only muffler we could find that
would fit the sled. You CANNOT use
an after-market muffler that was not
designed for this sled’s displacement and
expect it to work. Even though the air
pump changes the displacement effect,
the change is negligible to the muffler.
INSULATION
When selecting an insulation material, it
is very important to remember that
immediately after the combusted gases
exit the cylinder, they start to cool down.
As a result of this cooling, they will lose
velocity, in turn reducing the scavenging
effect of the cylinders. If you can
somehow keep the exhaust pipe gases at
a high temperature (close to combustion
temperature), you will maintain a higher
velocity, experience a higher pressure
drop in the system and get a better
efficiency.
After exploring many different options,
Cool IT, Thermo Tec exhaust insulating
wrap appeared to be the best choice for
insulation.
Thermo Tec Claims:
“The exhaust insulating wrap is an
innovative way to create more horsepower and
reduce underhood temperatures (by as much as
70%). Wrapping headers maintains hotter
exhaust gases that exit the system faster through
decreased density. Increased exhaust
scavenging is produced, along with lower intake
temperatures. It withstands continuous heat up
to 2000F, and contains no asbestos. Thermo Tec
exhaust wrap will not over insulate the system
when properly installed due to a proprietary
coating that conducts heat across the wrap’s
surface. This coating controls heat build-up and
dissipation. It is sold with a low profile 1/16”
thickness”
CONCLUSIONS &
RECOMMENDATIONS FOR
FUTURE WORK
As we are sure you can deduce from the
given information, two separate exhaust
pipes were built: one for optimal power
and another to actually fit on the
snowmobile. Because of a lack of local
resources, we were unable to fit the best
pipe to the sled. Hopefully, future
groups will find a way around this
problem.
The air pump increased volumetric flow
by 4% on the optimal pipe design and
approximately 2.5% to the fitted pipe,
so the air should ignite using the optimal
pipe dimensions as well. Use of an air
pump that gets you closer to a
stoichiometric reaction may also allow
you to further reduce hydrocarbons.
Beware of NOx though!!!
As said earlier, nitrogen oxides may be
increased if you boost the exhaust
temperature from the combustion of CO
and HC or if the added air enters the
cylinder during the overlap period when
both the intake and exhaust are open, in
turn leaning the mixture.
The belly (of the pipe currently on the
sled) should be shortened by exactly 1
while the convergent and divergent
cones should not be change at all. Refer
to Table 5 for all other dimensions.
Temperature profiles and data were
taken for both calculation purposes, as
well as finding whether or not the
injected air was ignited.
Appendix A
DynoJet Performance Results:
Horsepower & Torque Graphs for Stock
Pipe & Exhaust Prototypes
Stock exhaust compared with 1st and 2nd Prototype
3rd Prototype compared to Stock
4th Prototype compared with Stock pipe (RPMs)
4th Prototype compared with Stock pipe (MPH)
5th Prototype compared with Stock pipe (RPMs)
5th Prototype compared with Stock pipe (MPH)
6th Prototype compared with Stock pipe (MPH)
6th Prototype compared with Stock pipe (RPMs)
Final Pipe With muffler
Final Pipe with muffler & insulation
Final pipe with muffler, insulation and air pump
Comparison of power for the stock pipe, ideal prototype and final pipe
Comparison of Torque for the stock pipe, ideal prototype and final pipe
Appendix B
Data Acquisition using Daqbook 100s
with DBK-19 thermocouple cards and
specifications

DBK Thermocouple Card Specifications

Appendix C
Temperature Profiles for Snowmobile
Exhaust
Figure 1 shows the temperature profile for the stock snowmobile exhaust. Point 1 is
located at the header. Point 9 is located at the muffler. Point 7 is missing because the
thermocouple was damaged.
Figure 1
Temperature Profile for Stock Exhaust Pipe
0.00E+00
5.00E+01
1.00E+02
1.50E+02
2.00E+02
2.50E+02
3.00E+02
3.50E+02
4.00E+02
4.50E+02
5.00E+02
0.00E+00 1.00E+00 2.00E+00 3.00E+00 4.00E+00 5.00E+00 6.00E+00 7.00E+00
Time (seconds)
Temperature (F)
Point 1
Point 2
Point 3
Point 4
Point 5
Point 6
Point 8
Point 9
1
2
3
4 5 68
9
Thermocouple
Locations
Figure 2 shows the temperature profile for the first prototype exhaust with a sharp 60
degree angle at the head pipe.
Figure 2
Temperature Profile for First Prototype
0.00E+00
5.00E+01
1.00E+02
1.50E+02
2.00E+02
2.50E+02
3.00E+02
3.50E+02
4.00E+02
4.50E+02
5.00E+02
0.00E+00 1.00E+00 2.00E+00 3.00E+00 4.00E+00 5.00E+00 6.00E+00 7.00E+00
Time (seconds)
Temperature (F)
Point 1
Point 2
Point 3
Point 4
Point 5
Point 6
Point 8
Point 9
Figure 3 shows the temperature profile for the second prototype exhaust with a rounded
60 degree angle at the head pipe.
Figure 3
Temperature Profile for Second Prototype
0.00E+00
1.00E+02
2.00E+02
3.00E+02
4.00E+02
5.00E+02
6.00E+02
0.00E+00 1.00E+00 2.00E+00 3.00E+00 4.00E+00 5.00E+00 6.00E+00 7.00E+00
Time (seconds)
Temperature (F)
Point 1
Point 2
Point 3
Point 4
Point 5
Point 6
Point 8
Point 9
Table 1 shows the temperatures of the final fitted pipe with and without the air pump
operating. Temperatures were only taken at the two most important points, the head pipe
and the muffler. The dramatic increase in temperature with the air pump operating shows
the effects of burning more hydrocarbons before they are exhausted to the atmosphere.
Table 1
Without Air Pump With Air Pump
Head Pipe 499 F 601 F
Muffler 277 F 389 F
Bibliography
(1) How 2-Stroke Engines Work - Marshall Bain
(2) The Tuned Exhaust System - Adrian Teo, 1996
(3) Basic 2-Stroke tuning Eric Gorr
(4) Exhaust Pipe Theory Stephen Jordan
(5) Building Your Own Expansion Chambers Skalman
Racing
(6) How 2-Stroke Engines Work, & Why You should Care
Eric Murray
(7) Emissions From Combustion Engines & Their Control-
Patterson & Henein
(8) Emissions From 2-Stroke Engines Marco Nuti, 1998

SPECIFICATION OF HONDA MOTORCYCLE

2010-11-25T19:35:00.001-08:00

Absolute Revo 110 cc

çPanjang X lebar X tinggi ç: 1.925 x 709 x 1.084 mm
çJarak sumbu roda ç: 1.221 mm
çJarak terendah ke tanah ç: 147 mm
çBerat kosong ç : 98 kg (CW) ; 97 kg (Spoke)
çTipe rangka ç : Tulang punggung
çTipe suspensi depanç: Teleskopik
çTipe suspensi belakang ç: Lengan ayun dengan peredam kejut ganda
çUkuran ban depan ç : 70/90 - 17 M/C 38P
çUkuran ban belakang ç: 80/90 - 17 M/C 44P
çRem depan ç : Cakram hidrolik, dengan piston tunggal
çRem belakangç : Tromol
çKapasitas tangki bensin : 3,7 lt
çTipe mesin ç : 4 langkah, SOHC, pendinginan udara
çDiameter x langkahç: 50 x 55,6 mm
çVolume langkah ç: 109,1 cc
çPerbandingan kompresi ç: 9,0 :1
çDaya maksimum ç: 8,46 PS/7.500 rpm
çTorsi maksimum ç: 0,86 kgf.m/5.500 rpm
çKapasitas oli mesin ç: 0,8 lt pada pergantian periodik
çKopling Otomatis ç: Sentrifugal, tipe basah, dan ganda
çGigi transmsiç : 4 kecepatan bertautan tetap
çPola pengoperan gigi ç: Sentrifugal, tipe basah, dan ganda
çStarterç : Pedal dan Elektrik
çAkiç : MF 12 V - 3 Ah
çBusi ç: ND U20EPR9S, NGK CPR6EA-9S
çSistem pengapian ç: DC-CDI, Battery

Spesifikasi Beat

çPanjang X lebar X tinggi ç:ç1.859 x 876 1.053 mm
çJarak sumbu roda ç:ç1.240 mm
çJarak terendah ke tanah ç:ç156 mm
çBerat kosong ç:ç89,3 kg
çTipe rangka ç:çTulang Punggung
çTipe suspensi depanç:çTeleskopik
çTipe suspensi belakang ç:çLengan ayun dengan sokbreker tunggal
çUkuran ban depan ç:ç80/90 - 14 M/C 40P
çUkuran ban belakang ç:ç90/90 - 14 M/C 46P
çRem depan ç:çCakram hidrolik, dengan piston tunggal
çRem belakangç:çTromol
çKapasitas tangki bahan bakarç:ç3,5 liter
çTipe mesin ç:ç4 Langkah SOHC, pendinginan kipas
çDiameter x langkahç:ç50 x 55 mm
çVolume langkahç:ç108 cc
çPerbandingan kompresi ç:ç9,2 : 1
çDaya maksimum ç:ç8,22 PS / 8.000 rpm
çTorsi maksimum ç:ç0,85 kgf.m / 5.500 rpm
çKapasitas minyak pelumas mesin ç:0,7 liter pada penggantian periodik
çKopling Otomatis ç:çOtomotis, Sentrifugal, type kering
çGigi transmsiç:çOtomatis, V-Matic
çPola pengoperan gigi ç:ç-
çStarterç:çElectric & Kick Starter
çAkiç:çNF Battery, 12 V - 3,5 Ah
çBusi ç:çND U 24 EPR9 / NGK CPR8 EA-9
çSistem pengapianç:çDC - CDI, Battery

Spesifikasi Blade

çPanjang X lebar X tinggi ç:ç1855 x 709 x 1071 mm
çJarak sumbu roda ç:ç1221mm
çJarak terendah ke tanah ç:ç147 mm
çBerat kosong ç:ç96,8 kg
çTipe rangka ç:çTulang Punggung
çTipe suspensi depanç:çTeleskopik
çTipe suspensi belakang ç:çLengan Ayun - Shock Breaker Ganda
çUkuran ban depan ç:ç70/90 - 17 M/C 38P
çUkuran ban belakang ç:ç80/90 - 17 M/C 44P
çRem depan ç:çCakram Hidrolik Piston Tunggal
çRem belakangç:çTromol
çKapasitas tangki bahan bakarç:ç3,7 Liter
çTipe mesin ç:ç4 Langkah,SOHC
çDiameter x langkahç:ç50 x 55,6 mm
çVolume langkahç:ç109,1 cc
çPerbandingan kompresi ç:ç9,0 : 1
çDaya maksimum ç:ç8,46 PS/ 7500 rpm
çTorsi maksimum ç:ç0.86 Kgfm / 5500 rpm
çKapasitas minyak pelumas mesin ç:ç0,8 liter
çKopling Otomatis ç:çGanda, otomatis, sentrifugal, tipe basah
çGigi transmsiç:ç4 kecepatan rotari
çPola pengoperan gigi ç:çRotari/ bertautan tetap
çStarterç:çElectric starter & kick starter
çAkiç:çMF Battery, 12V - 3,5 Ah
çBusi ç:çND U20EPR9S, NGK CPR6EA-9S
çSistem pengapianç:çDC - CDI, Battery

Spesifikasi City Sport 1

çPanjang X lebar X tinggi ç:ç1.923 x 682 x 1.042 mm
çJarak sumbu roda ç:ç1.251 mm
çJarak terendah ke tanah ç:ç130 mm
çBerat kosong ç:ç114 kg
çTipe rangka ç:çTwin Tube Frame
çTipe suspensi depanç:çTeleskopik
çTipe suspensi belakang ç:çTunggal ( Monoshock )
çUkuran ban depan ç:ç70/90 - 17 M/C 38P
çUkuran ban belakang ç:ç80/90 - 17 M/C 44P
çRem depan ç:çCakram hidrolik dengan piston ganda
çRem belakangç:çCakram hidrolik dengan piston tunggal
çKapasitas tangki bahan bakarç:ç4,1 liter
çTipe mesin ç:ç4 langkah, OHC, pendingin air
çDiameter x langkahç:ç58 x 47,2 mm
çVolume langkahç:ç124,7 cc
çPerbandingan kompresi ç:ç10,7 : 1
çDaya maksimum ç:ç12,8 PS / 10.000 rpm
çTorsi maksimum ç:ç1.04 kgf.m / 7500 rpm
çKapasitas minyak pelumas mesin ç:1,0 liter pada penggantian periodik
çKopling Otomatis ç:çManual. multiplate wel clutch
çGigi transmsiç:ç5 kecepatan
çPola pengoperan gigi ç:ç1-N-2-3-4-5
çStarterç:çElectrik Starter & Kick Starter
çAkiç:çMF, 12 V - 3,5 A.h
çBusi ç:çND U24ESR-N / NGK CR8E
çSistem pengapianç: DC - CDI

Spesifikasi mega Pro

çPanjang X lebar X tinggi ç:ç2.034 x 754 x 1.065 mm
çJarak sumbu roda ç:ç1.281 mm
çJarak terendah ke tanah ç:ç149 mm
çBerat kosong ç:ç126 kg (tipe spoke) / 127 kg (tipe CW)
çTipe rangka ç:çPola Berlian (diamond steel)
çTipe suspensi depanç:çTeleskopik
çTipe suspensi belakang ç:Lengan ayun dan peredam kejut dapat disetel pada 5 posisi
çUkuran ban depan ç:ç2,75 - 18 - 42P
çUkuran ban belakang ç:ç3,00 - 18 - 47P
çRem depan ç:çTipe cakram hidrolik, dengan piston ganda
çRem belakangç:çTromol
çKapasitas tangki bahan bakarç:ç13,2 liter
çTipe mesin ç:ç4 langkah, SOHC, pendinginan udara
çDiameter x langkahç:ç63,5 x 49,5 mm
çVolume langkahç:ç156,7 cc
çPerbandingan kompresi ç:ç9,0 : 1
çDaya maksimum ç:ç13,3 PS / 8.500 RPM
çTorsi maksimum ç:ç1,3 kgf.m / 6.000 RPM
çKapasitas minyak pelumas mesin ç:0,9 liter pada penggantian periodik 0,9 liter pada penggantian periodik
çKopling Otomatis ç:çManual, tipe basah dan pelat majemuk
çGigi transmsiç:ç5 kecepatan, bertautan tetap
çPola pengoperan gigi ç:ç1-N-2-3-4-5
çStarterç:çPedal dan starter elektrik
çAkiç:ç12 V - 5 Ah
çBusi ç:çND X 24 EP-U9 / NGK DP8EA-9
çSistem pengapianç:çDC-CDI, Baterai

Spesifikasi Supra X 125 PGMFI

çPanjang X lebar X tinggi ç: ç1.889 x 702 x 1.094 mm
çJarak sumbu roda ç: ç1.242 mm
çJarak terendah ke tanah ç: ç136 mm
çBerat kosong ç: ç107 kg
çTipe rangka ç: çTulang punggung
çTipe suspensi depan ç: çTeleskopik
çTipe suspensi belakang ç: çLengan ayun dan peredam kejut ganda
çUkuran ban depan ç: ç70/90 - 17 M/C 38P
çUkuran ban belakang ç: ç80/90 - 17 M/C 44P
çRem depan ç: çCakram double piston
çRem belakang ç: çCakram single piston
çKapasitas tangki bahan bakar ç: ç3,7 liter
çTipe mesin ç: ç4 langkah, SOHC, pendinginan udara
çDiameter x langkah ç: ç52,4 x 57,9 mm
çVolume langkah ç: ç124,8 cc
çPerbandingan kompresi ç: ç9,0 : 1
çDaya maksimum ç: ç9,18 PS/7.500 rpm
çTorsi maksimum ç: ç0,99 kgf.m /5.000 rpm
çKapasitas minyak pelumas mesin ç: 0,7 liter pada penggantian periodik
çKopling Otomatis ç: çOtomatis sentrifugal
çGigi transmsi ç: çkecepatan bertautan tetap
çPola pengoperan gigi ç: çN-1-2-3-4-N (rotari)
çStarter ç: çPedal dan elektrik
çAki ç: ç12 V - 3,5 Ah
çBusi ç: çND U20EPR9 / NGK CPR6EA-9
çSistem pengapian ç: çFull transistorized

Spesifikasi Supra-X125

çPanjang X lebar X tinggi ç:ç1.889 x 702 x 1.094 mm
çJarak sumbu roda ç:ç1.242 mm
çJarak terendah ke tanah ç:ç138 mm
çBerat kosong ç:ç105kg / 103 (Tipe Spoke)
çTipe rangka ç:çTulang punggung
çTipe suspensi depanç:çTeleskopik
çTipe suspensi belakang ç:çLengan ayun dan peredam kejut ganda
çUkuran ban depan ç:ç70/90 - 17M / C 38P
çUkuran ban belakang ç:ç80/90 - 17M / C 44P
çRem depan ç:çCakram double piston
çRem belakangç:çCakram single piston / Tromol (Tipe Spoke)
çKapasitas tangki bahan bakarç:ç3,7 liter
çTipe mesin ç:ç4 langkah, SOHC, pendinginan udara
çDiameter x langkahç:ç52,4 x 57,9 mm
çVolume langkahç:ç124,8 cc
çPerbandingan kompresi ç:ç9,0 : 1
çDaya maksimum ç:ç9,3 PS / 7.500 rpm
çTorsi maksimum ç:ç1,03 kgf.m / 4000 rpm
çKapasitas minyak pelumas mesin ç:0,7 liter pada penggantian periodik
çKopling Otomatis ç:çOtomatis sentrifugal
çGigi transmsiç:çKecepatan bertautan tetap
çPola pengoperan gigi ç:çN-1-2-3-4-N (rotari)
çStarterç:çPedal dan elektrik
çAkiç:ç12 V - 3,5 Ah
çBusi ç:çND U20EPR9 / NGK CPR6EA-9
çSistem pengapianç:çCarburator - DC CDI

Spesifikasi Tiger

çPanjang X lebar X tinggi ç: ç2.029 x 747 x 1.093 mm
çJarak sumbu roda ç: ç1327 mm
çJarak terendah ke tanah ç: ç155 mm
çBerat kosong ç: ç138 kg
çTipe rangka ç: çPola Berlian
çTipe suspensi depan ç: çTeleskopik
çTipe suspensi belakang ç: Lengan ayun pegas ganda dengan tabung oli
çUkuran ban depan ç: ç2,75 - 18 42L
çUkuran ban belakang ç: ç100/90 - 18 M/C - 56P
çRem depan ç: çCakram hidrolik, dengan piston ganda
çRem belakang ç: çCakram hidrolik, dengan piston tunggal
çKapasitas tangki bahan bakar ç: ç13,2 Liter
çTipe mesin ç: ç4 Langkah OHC, pendinginan udara
çDiameter x langkah ç: ç63,5 x 62,2 mm
çVolume langkah ç: ç196,9 cc
çPerbandingan kompresi ç: ç9,0 : 1
çDaya maksimum ç: ç16,7 PS / 8.500 RPM
çTorsi maksimum ç: ç1,60 kg.m / 7.000 RPM
çKapasitas minyak pelumas mesin ç: 1,0 liter pada penggantian periodik
çKopling Otomatis ç: çManual, Multiplate Wet Clutch
çGigi transmsi ç: ç6 kecepatan
çPola pengoperan gigi ç: ç1-N-2-3-4-5-6
çStarter ç: çElektrik Starter & Kick Starter
çAki ç: ç12 V - 7 Ah
çBusi ç: çND x 24 EP U9 / NGK DP8EA-9
çSistem pengapian ç: çCDI-AC, Magneto

Spesifikasi Vario

çPanjang X lebar X tinggi ç: ç1.897 x 680 x 1.083 mm
çJarak sumbu roda ç: ç1.273 mm
çJarak terendah ke tanah ç: ç132.5 mm
çBerat kosong ç: 99,9 kg (tipe spoke) 99,3 kg (tipe CW)
çTipe rangka ç: çTulang Punggung
çTipe suspensi depan ç: çTeleskopik
çTipe suspensi belakang ç: çLengan ayun dengan sokbreker tunggal
çUkuran ban depan ç: ç80/90 - 14 M/C 40P
çUkuran ban belakang ç: ç90/90 - 14 M/C 46P
çRem depan ç: çTipe cakram hidrolik dengan piston ganda
çRem belakang ç: çTromol
çKapasitas tangki bahan bakar ç: ç3,6 Liter
çTipe mesin ç: ç4 Langkah, SOHC
çDiameter x langkah ç: ç50,0 mm x 55,0 mm
çVolume langkah ç: ç108 cc
çPerbandingan kompresi ç: ç10,7 : 1
çDaya maksimum ç: ç8,99 PS / 8000 rpm
çTorsi maksimum ç: ç0,86 kgf.m / 6.500 RPM
çKapasitas minyak pelumas mesin ç: 0,7 Liter pada penggantian periodik
çKopling Otomatis ç: çOtomatis sentrifugal, tipe kering
çGigi transmsi ç: çOtomatis, V-Matic
çPola pengoperan gigi ç: ç-
çStarter ç: çPedal dan elektrik
çAki ç: ç12 V - 3,5 Ah
çBusi ç: çND U22FER9 / NGK CR7EH-9
çSistem pengapian ç: çDC - CDI, baterai
çTinggi tempat duduk : ç758 mm
çSistem pendingin ç: Silinder tunggalPendingin dengan cairan (liquid cooled)
çSusunan silinder ç: çSilinder tunggal
çKarburator ç: çVK22 x 1
çLampu depan ç: ç12 V 25 W / 25 W x 2
çLampu senja ç: ç12 V 3,4 W x 2

tune engine with nitro

2010-11-25T19:33:00.001-08:00

Nitro Engine Tuning
MAXIMIZE YOUR ENGINE'S POWER POTENTIAL
So now you can get your engine started on a regular basis, but you're still struggling with the fine-tuning that will score you a win at the racetrack (or bragging rights at the parking lot). Properly tuning a nitro engine can make that difference without jeopardizing its health. It takes time to learn how to really tune your engine, however. There's a certain "feel" to how your car drives and a certain sound you'll come to know when your engine has been ideally tuned. Other cues that you feel and hear tell you what to adjust when your engine isn't running properly. When it's time to tune your engine, there's no substitute for plain old experience. Reading about engine tuning is helpful, but you need to experiment with your engine to improve your tuning skills. The good news is that the following tips will help you avoid some of the pitfalls of fine-tuning and achieve tuning proficiency more quickly.
BASE-LINE MIXTURE SETTINGS
Engine manufacturers often include base-line settings for the mixture needles, so it's wise to start with these. If this information is not provided, then you must arrive at needle settings that will get the engine started. A universal starting point is usually about 1 turn open (counter clockwise) on the low-speed needle and somewhere in the 2- to 3-turn range on the high-speed needle. This varies among engines, but it gets you started running, and then you can make the necessary corrections. After the initial start-up, follow the proper break-in procedure, and then worry about performance tuning!
The proper sequence for adjusting the mixture needles is hotly debated. When you start to fine-tune the engine, it's generally best to start with the high-speed needle, then set the low-speed. First, however, get your engine running, and keep it running before you worry about race tuning.
During break-in, the engine typically idles a long time, so it's best to adjust the low-speed setting first so the engine runs slightly rich (loading up every 30 seconds or so). It requires an occasional "blip" of the throttle to clear out any raw fuel that has accumulated in the engine. Once break-in is finished, then get the high-speed needle in the ballpark.
Place the car on the ground and accelerate smoothly to give the engine a chance to build some heat. With the high-speed needle in the proper range, the engine should be able to rev relatively well up to full speed once it has been running for a few minutes on the track or parking lot.
FINE-TUNING
A word of caution first: there's a fine line between the perfect tune and a blown or damaged engine. Nitro-engine fuel also contains engine lubricant, so as you get close to dialling in the mixture to where there is just enough fuel to burn and deliver maximum power, you also are close to having just enough oil to keep the engine lubricated. Anyone with experience in tuning 2-stroke engines can tell you that they run best right before they seize or blow up. Our engines are a little tougher and more capable of taking some abuse than bigger 2-strokes, but there's no sense in pushing the mixture settings so lean that you risk damage to the engine. I can't say this too often: get the engine up to full running temperature by running the car exactly as you would on the track or parking lot. The high-speed needle setting depends on the type of driving you do. I'll start with a racing setup.
HIGH-SPEED NEEDLE
Racers will tune the high-speed setting to get from point A to point B as quickly as possible. (Performance also depends on a proper low-speed needle setting, but for now, let's concentrate on the high-speed setting.) The best place to race tune your engine is on the track where you run. I prefer to set the high-speed mixture so the car can leg out the track's longest straight section in the shortest time. Estimate the time by "feel" and gut instinct, or use a stopwatch for more accuracy. The high-speed mixture should be set to maximize engine performance for that particular track configuration. A short, tight track may require a main mixture setting just a shade on the lean side to provide maximum power out of the corners. You needn't be concerned about high-rpm performance because the track is too small for the engine to ever reach peak rpm. A long, high-speed track may require a slightly rich main-needle setting. If an engine constantly revs at the upper limits of the rpm range, the fuel mixture should be richened to ensure proper lubrication across the entire rpm range. This slightly rich setting might reduce bottom-end acceleration to a degree, but longer tracks require a slightly richer mixture setting to let the engine rev to its limits without running dry of fuel and oil.
Why is it important to tune the engine to the track? A mixture needle can only provide optimum performance within a relatively narrow rpm range. Anywhere below this hypothetical rpm range, the engine runs slightly rich; anywhere above, it gets progressively leaner. Until we have fuel injection that constantly optimizes fuel mixture throughout the rpm range, there needs to be a degree of compromise with the mixture settings. So, ideally, set the mixture to provide the most power in an rpm range that is best suited to the track on which you run.
WIDE-OPEN RUNNING
Running in parking lots, particularly larger ones with a lot of breathing room, requires unique mixture settings. It's a common mistake to establish mixture settings for maximum punch—as though the car will be run within the confines of a tight racetrack—and then to go out and run at wide-open throttle (WOT) in a huge parking lot for 5 minutes. This type of running is incredibly unhealthy for an engine to begin with, and compounding the problem with an excessively lean main-needle setting is a recipe for disaster. If you still insist on torturing your engine, the high-speed mixture setting needs to be as much as 1/4 turn richer than typical to provide optimum fuel for the upper rpm range. The engine will be a little softer when accelerating from a standstill, but it's the only way to ensure there is an adequate supply of fuel and oil when running at the upper end of the rpm range. The inherent danger is that this type of running taxes the connecting rod and other engine components to their limits, but having the proper mixture setting will at least delay the inevitable.
LOW-SPEED NEEDLE
The high-speed needle is dialled in, so now let's properly set the low-speed needle. It's important to set it last because it simply regulates the fuel that flows from the main needle at low throttle settings. Lean out the main needle, and you automatically lean the low-speed needle as well. For this reason, it's wise to finish with the low-speed setting.
Again, it's imperative for the engine to be at full operating temperature. There are many methods of testing the low-speed needle setting; one is to pinch the fuel line. When you pinch the fuel line, the engine rpm increase slightly. Keep pinching it, and the engine will eventually stall. If the engine rpm increase dramatically, it indicates that the low-speed setting may be too rich. Or, if the low-speed setting is already too lean, the engine rpm may not increase much at all, and the engine will stall rather quickly. It's a somewhat crude method and doesn't tell you what to expect from the engine on the track, but it will get you into the ballpark.
Another common way is the "see-how-long-it-will-idle" method. The low-speed needle adjustment affects how long the engine will idle. A too lean fuel mixture causes the engine to race and possibly stall, limiting the duration of a steady idle. A too rich low-speed-mixture setting causes the engine idle to steadily drop and eventually stall. The ideal setting allows the engine to hold a smooth, steady idle for 10 to 20 seconds (max), and then the engine rpm decrease steadily because the crankcase loads up with fuel. Why? There are no awards given for the longest-idling engine. If the engine is able to idle steadily for a longer time, then it may start to lean out and heat up during a race and make it difficult to drive the car and keep the engine running. The only flaw in this method is that it doesn't tell you whether you have an artificially rich mixture to compensate for an idle speed that's too high.
A common mistake is to set the idle-speed screw to keep the carburettor open too far. The low-speed needle must then be artificially rich to bring the idle down to a reasonable rpm. The symptoms are similar to a too rich low-speed-mixture setting; there's just a delay in the loss of engine rpm. How do you avoid this? This is also something that becomes easier with experience, but just continue to reduce the idle speed and lean the mixture until you know you can't go any further. Bottom line: adjust the idle-speed screw to suit the fuel-mixture setting, not the other way around.
The simplest and most foolproof method to properly set the low-speed mixture is, again, to do it on the track. Set the low-speed needle so your car gets the strongest launch after sitting still for about 10 seconds. The engine should be able to pull strongly off the line without hesitation. A noticeable hesitation might be the result of either a rich or a lean low-speed mixture; knowing the difference takes experience, but look for signs that help point you in the right direction. How an engine decelerates can tell you as much as how it accelerates. If the engine spools down and rpm drops uncharacteristically low, it indicates that the low-speed-mixture setting is too rich. Or, if the engine takes too long to reach a steady idle and seems to want to keep revving, that tells you the low-speed-mixture setting is too lean. It can also indicate a lean high-speed-mixture setting, but that setting should have been addressed by properly setting the high-speed mixture first.
It will take a little time to get it right. If you make small adjustments and are patient, you really can't do anything wrong. An adjustment you make in the wrong direction is reflected in engine performance; to correct the problem, simply go the other way.
CHANGING FUEL
Changing to a higher percentage of nitro fuel sounds like an easy method of developing more horsepower, but it isn't always that simple. Without getting into all the particulars of nitro fuel, I'll just say that there is a point where you can have too much nitro. Adding up to 10 percent more nitro than is typical produces more power, but you have to know how to adjust your engine to accommodate the extra nitro. Fuel-mixture settings need to be slightly richer when nitro content is increased. Also, you may have to increase head clearance by adding an extra head shim. The extra fuel introduced into the combustion chamber increases compression by adding non-compressible matter; this also increases
cylinder pressure during the combustion process, which may cause detonation. Detonation occurs when the fuel explodes instead of burning, and that can cause internal engine damage. The extra head shim will likely prevent detonation when fuel with higher nitro content is used.
A final note about fuel: fuel with a lower oil content (for manufacturers that actually disclose the amount of oil in their fuels) should be run with a richer mixture setting. This doesn't so much relate to performance as it does to the benefit of the engine. Conversely, fuels with higher oil content have the extra lubrication that allows a leaner mixture setting with less risk of engine damage. Fuels with a lower concentration of lubricant are intended for competition use by experienced engine tuners. These fuels will make marginally more power because the lubricant that's removed is replaced with power-producing nitro and methanol. Evaluate your tuning ability honestly before you run out to buy fuel with lower oil content.
GLOW PLUG
A glow plug's temperature range is critical to proper performance. Small-block engines generally use warm to hot glow plugs, while big-block engines use plugs in the colder range. If you choose a plug in the wrong temperature range, you could be chasing the tune of your engine till the sun goes down. Changes of the relative temperature of the glow plug can be beneficial, however.
A combination of compression, heat and a catalytic reaction between the platinum in the glow-plug coil and the methanol in the fuel creates combustion in a nitro engine. Altering the heat range of your glow plug can alter the timing of the combustion process. Nitro engines don't have an ignition system that can be used to advance or retard combustion timing, but a hotter plug that causes ignition a little earlier in the combustion process can have the same effect. "Advancing" the ignition timing can increase overall power output, especially at higher rpm. There are limits, however, and installing too hot a plug causes pre-ignition (detonation) and risks damaging your engine.
It's a challenge to figure out a glow plug's temperature range. Manufacturers don't use a consistent and universal standard to rate the temperature ranges of their glow plugs. You will probably know the temperature of a plug relative to others within a given product line, but currently, no rating system allows comparisons among manufacturers. Here again, plain old experience with a variety of glow plugs will help you to know which are best for the effect you want.
"Reading" the glow plug is a tuning technique advanced by Ron Paris. It suggests that looking at the glow plug tells you something about how your engine is running. The element in a glow plug will turn gray in an engine that is close to the optimum fuel mixture. This method requires a new glow plug, as the element will eventually turn gray regardless of the needle settings; the length of time it takes to turn gray is the issue. Plugs that turn gray in just a tank or two of fuel (running at race pace, not diddling around) indicate a fuel mixture close to ideal—but also close to trouble. If the plug stays wet and shiny for a few tanks of fuel, you're in the safe zone; a little rich but safe. When the plug wire gets distorted or broken, however, you're in real trouble. It's a sure sign that the mixture is way too lean, or that there is too much compression and the engine is detonating.
HEAD SHIMS
Engines are essentially air pumps. The engine takes air in, mixes it with fuel, and then the mixture is compressed and ignited. The additional pressure created by the burning fuel increases by a factor directly related to the amount of compression: increasing compression increases power output. But there are limits to the compression an engine tolerates. Too much causes the fuel mixture to combust too quickly, and that returns us to the same detonation scenario of an excessively hot glow plug.
The amount of compression is determined by the number and thickness of the shims (gaskets) between the cylinder head and the top of the piston sleeve. Well, it's determined by many other factors, but the only one easily changed is the head clearance via head shims. More shims = less compression; less shims = more compression. Removing or replacing shims with thinner ones increases compression. Some engines have only one shim, so it isn't advisable to run without a shim at all. Moderation is the key. Go slowly, and make small, not drastic, changes that will minimize the risk of damage to your engine. First and foremost, be sure the piston won't hit the cylinder head if you remove a shim (or shims).
You can also change compression with glow plugs. Some manufacturers make a longer glow plug that protrudes slightly into the combustion chamber, effectively reducing the area in which the fuel mixture is compressed. This area is already small, and the little extra space occupied by a longer glow plug will raise compression. This is not the most desirable method, but it can be used on engines that have only one thin head shim. It's unlikely that the longer plug will even come into contact with the piston, but just to be safe, check the head clearance before you install a long plug.
WEATHER CONDITIONS
It's a simple fact: for optimum performance, you must retune your nitro engine every time you run it. Anyone who assumes that the needles can be left alone once they have been set is sadly mistaken. An overnight change in weather conditions may prevent an engine from running or may put it at risk of some damage if adjustments aren't made to the fuel-mixture settings. Ignoring an engine's tuning needs compromises its ability to make horsepower. In response to certain changes in weather, equipment and other variables, nitro engines must be regularly retuned.
Temperature. Hot weather requires a leaner mixture setting; cold weather requires a richer setting. Most people assume the opposite because they treat the mixture needle like a thermostat. It is wrong to assume that colder weather requires a leaner setting to keep heat in the engine and vice versa. Cold air is denser than hot air. The denser, colder air packs more oxygen into the engine, so going from hot weather to cold needs a commensurate increase of fuel to balance ratio of fuel-burning oxygen and the fuel itself. The opposite is true in hotter weather. Going from cold to hot weather requires a leaner mixture setting.
Humidity. Humidity is the amount of moisture (water vapor) in the air. Moisture in the air takes up volume that would otherwise be occupied by fuel-burning oxygen. Less oxygen means less fuel is required to maintain a proper ratio of air and fuel. High humidity requires a leaner mixture setting than dry conditions.
Barometric pressure. A barometer measures the atmospheric pressure (generally listed in the local newspaper or on the local weather forecast on TV). Higher barometric pressure readings mean more air is getting into the engine, requiring a richer mixture setting to balance the air/fuel ratio.
Altitude. Altitude is an important factor that most of us ignore, yet it affects the engine's performance possibly more than any other element. The general formula for power loss with increases in altitude is 3 percent for every 1,000 feet above sea level. If you race in Colorado at 5,000 feet instead of in California at sea level, you can expect to lose about 15 percent of the engine's potential power output, if the engine is tuned properly.
Air is thinner at higher altitudes, which means there's less fuel-burning oxygen than at sea level. You might sense a common theme here: less air (oxygen) means less fuel to maintain the proper air/fuel ratio. So, running at higher altitudes requires a leaner mixture setting than running at sea level.
TUNING
This chart indicates the direction in which you should adjust the fuel mixture when faced with changing weather and other conditions. It assumes the engine is currently well tuned. You could face any combination of conditions listed in the chart; knowing which way to go with the mixture adjustments is half the battle.
Higher air temperature Lean
Lower air temperature Rich
Higher humidity Lean
Lower humidity Rich
Higher barometric pressure Rich
Lower barometric pressure Lean
Higher altitude Lean
Lower altitude Rich
Higher nitro content Rich
Lower nitro content Lean
Higher oil content Lean
Lower oil content Rich
Hotter glow plug Rich
Colder glow plug Lean
TUNED PIPE AND HEADER
Anyone who has been around 2-strokes knows that the exhaust system plays a major role in engine performance. Pipes and how they affect performance is a complete article in itself. I don't want to get into the science of tuned pipes here, I'll simply suggest that volume (assuming the pipe doesn't stray too far from convention) determines where the pipe will go to make the best power. Smaller pipes with lower overall volume make the best top-end power, while the fatter, longer pipes with greater volume provide the best bottom-end punch. Selecting the proper tuned pipe can have a very noticeable impact on your application.
Headers can be modified by almost any enthusiast. The length of the header is important to squeezing more power out of your engine. Longer headers deliver better bottom-end power, while shorter headers
make better top end. Shorten a header by cutting it with a hacksaw or a Dremel tool. Cut it in 1/8-inch increments, and measure the performance to determine whether any improvement has occurred. Continue cutting until performance levels off. If you need to add back on to the length of the header because you've cut too much and performance is suffering, simply increase the gap between the header and pipe, but don't expose more than 1/4 inch of coupler. If the header is too short by greater than 1/4 inch, just get a new one.
CLUTCH
I've spent lots of time trying to chase away a nasty bog in the engine as it came off the line or out of a corner, only to find later that the problem was the clutch. Some clutches are built properly at the factory, but in my experience, most engage too early, which hobbles the engine coming out of every corner. Tuning the clutch to engage at the proper rpm puts more power to the ground than most could imagine.
TEMPERATURE GAUGE
You'll notice that I have not once mentioned a temperature gauge. The worst thing you can do is to tune an engine to run at a specific temperature. Engine temperature is affected by a number of factors, only one of which is fuel mixture. Weather and many other factors play a role in engine temperature, so tuning to run at the same temperature every time short changes the engine's potential to make power. Yes, most engines run in the 93c to 148 degree c range, so checking that the engine stays within this range is valuable to a certain extent. As a result of different weather conditions and other variables, however, the same engine—when tuned for peak power output—can vary as much as 10 degrees Celsius. A temp gauge is a reference tool that you should use only to build a data bank of tuning information. A temp gauge should not be used as a tuning tool. Don't tune an engine to run at 230 degrees all the time. Prevailing conditions may require a mixture setting that causes the engine to make maximum power while running at 132 degrees Celsius. You'll never know that if you always target the same temperature.
CONCLUSION
Engine tuning is not a black art; it just takes time to learn the particulars so you can maximize your power plant's performance. Take the time to read and learn, and you will avoid the mistakes most of us made in learning the ropes. We never really stop learning; sometimes, we just get too smart for our own good. Experiment a little with some of the tips, and you'll find there's more power to be made with less effort than you thought. Some of the modifications involve a bit of risk; just take it slowly, and use your "noodle." It's hard to make a mistake you can't correct.

FIM ASIA ROAD RACING CHAMPIONSHIP 2007

2010-11-25T19:30:00.001-08:00

FIM ASIA ROAD RACING
CHAMPIONSHIP 2007
MACHINE SPECIFICATION FOR 115cc (UNDERBONE)
(4-stroke horizontal layout engine)
1. CLASSES
Classes Engine Capacity Stroke Max. no.
of cylinder
Max. Number
of Gear
115CC Up to 115CC 4 1 6
2. GENERAL SPECIFICATION
2.1 Motorcycle for SS Class Underbone must correspond to motorcycles of current
production and must be homologated by the respective Asian FMN.
2.2 Motorcycles must conform to all regulations for Underbone class and must be of
half front fork type only. (Full fork like sport model / separate handlebar are strictly
not allowed)
2.3 The maximum width of rims must be as follows :-
Class Front Rear
115cc 2.5 inch 3.0 inch
2.4 Cast alloy wheels are allowed with the minimum gross weight for :
Front: 6.0kg
Rear: 6.5kg
(Gross weight includes the disc brake and brake hub for rear tyre with drum brakes,
tyre, rim and hub, excluding the sprocket and sprocket hub)
2.5 The following items MUST NOT BE altered
2.5.1 Type of engine, number of cylinder, piston stroke and the number valve.
2.5.2 The material and casting of cylinder, cylinder head, crankcase and gear
box.
2.5.3 The materials of the internal parts of the engines.
2.5.4 The materials, casting and shape of crankcase cover.
2.5.5 The materials, dimensions and shapes of crankshaft assembly.
2.5.6 Fuel tank (excluding inlet opening and fuel cork)
2.5.7 Primary gear ratio & number of gears.
2.5.8 Frame body, rear swing arm & rear suspension system
2.5.9 Frame body must remain as originally produced by the manufacturer
2.5.10 Front Fork and under bracket complete.
FIM ASIA ROAD RACING
CHAMPIONSHIP 2007
2.6 The following items MAY BE ALTERED, but must conform to the general
specification.
(This is for clarification only. Other parts not listed in Art. 2.5 & 2.6 can be altered or
replaced. Change of specification means modification, changes or removal of the
parts.)
2.6.1 Change of compression ratio is allowed.
2.6.2 Setting of carburetor, attachment or size change of air funnel.
2.6.3 Inlet opening of fuel tank for fuel charge may be modified but cannot be
relocated.
2.6.4 Change of fuel pipe and fuel cork.
2.6.5 Change of exhaust pipe and muffler, but must have silencer.
2.6.6 Material of clutch discs and specifications of spring. Hand clutch is allowed.
2.6.7 Gear ratios are free.
2.6.8 Starting device and parts relative to this device may be removed.
2.6.9 Modification or removal of air cleaner box, wire harness and control wires.
2.6.10 Removal of speedometer (including meter gearbox and cable.)
2.6.11 Removal of drive chain case and cover. Change of drive chain is allowed.
2.6.12 Change of final gear ratio is allowed.
2.6.13 Attachment of bead stopper and balance weight to tyre.
2.6.14 Modification and change of rear brake part is allowed.
2.6.15 Frame body may be strengthened.
2.6.16 Modification and change to brackets and pedals including footrest.
2.6.17 Front suspension unit must remain as originally produced by the
manufacturer. However, the following internal parts of the fork can be
modified: Shims, hydraulic piston, oil passages, springs and spacers.
2.6.18 Attachment of stabilizer to strengthen or reinforcing rear swing arm is
allowed.
2.6.19 Removal of dust seals.
2.6.20 Rear suspension unit must remain as originally produced by the
manufacturer. However rear suspension unit is free. The rear linkage must
remain as originally produced by the manufacturer.
2.6.21 Handle bars, clutch and front brake lever may be changed by an after market
copy. Clutch springs may be changed.
2.6.22 Steering dampers may be fitted. They must not act in any way as a steering
lock limiting device.
2.6.23 Materials of streamlining and material of seat cowling. (However, expensive
materials such as carbon fibre and kevlar are not allowed).
2.6.24 Removal of rear mudguard and side cover. Front mudguard may be cut but
not less than 6 inches from the front fork on original part.
2.6.25 All lubricants are free
2.6.26 Adjusting and polishing any parts are allowed.
Adjusting is defined as: �To select each part or assembly complete with-in
the limit of single or total tolerance� (i.e. that of valve clearance, ignition
timing etc.)
2.6.27 Cutting unnecessary stays is allowed (including part of seat-rail)
2.6.28 Flywheel and ignition is free.
FIM ASIA ROAD RACING
CHAMPIONSHIP 2007
2.6.29 Front disc brake may be added. The front fork must be standard but may be
modified to incorporate the disc. Change of front forks is permitted only for
same makes of underbone for the purpose of incorporating the front disc.
2.6.30 Camshaft, timing chain, and cam sprockets and connecting rod may be
modified.
2.6.31 Leg shield may be shaved at the edge from the standard size only for
cornering purposes
2.6.32 Cylinder head must remain original visually but can be modified
2.6.33 Maximum permitted valve size is 29mm
2.6.34 Front mudguard may be cut but not less than 6 inches from the front cowling
2.6.35 Carbon fibre silencer sleeves are permitted
2.7 Weight
The minimum half dry weight without fuel for the rider�s with full gears and bike is
135kgs.
Motorcycle without fuel 75kgs
Rider�s Minimum Weight with full gear (Racing
Suit, Gloves, Helmet and Booths etc.)
60kgs
Please note that if the rider�s minimum weight with full gears is less than 60kgs, a
penalty of maximum of 5kgs must be added onto the motorcycle to equal 135kg.
However no additional weight will be added should the total weight still be less than
135kg after the penalty is imposed. All ballast added to the bike must be securely
fitted. Sprocket will not be allowed to be use as weight ballast unless permanently
welded on the bike.
* Half dry weight means: Motorcycle ready to race without fuel. In case of separate
lubricant oil, it�s regarded as fuel.
2.8 The following items MUST BE ALTERED if the homologated motorcycle does
not comply.
2.8.1 Motorcycles must be equipped with a functional ignition kill
switch. (with-in reach of hands while hand grips).
2.8.2 Removal of safety equipment
i.e. stands, rear view mirror, auxiliary steps and turn signals.
2.8.3 All drain plugs must be wired. All parts of external oil pressure line must be
safety wired.
2.8.4 Maximum size of carburetor is 24mm. Minimum cross sectional area of
intake mixture air passage. Jet needle, butterfly shaft, valves. Throttle valve
shapes and its sectioned area is not concerned.
2.8.5 All breather hose must have a catch tank located in as easily accessible
position and which must be emptied before the start of each race. Catch tank
must measure at least 250cc.
FIM ASIA ROAD RACING
CHAMPIONSHIP 2007
2.9 The following will be prohibited in any case.
2.9.1 Use of special materials such as
Magnesium light alloy, titanium alloy, reinforced carbon fibre, etc. when
modifying or changing parts.
2.9.2 Light alloy in the construction of
Front and rear wheel spindle (shaft).
2.9.3 Tyres are free. slick, hand cut or rain tyres are not allowed.
2.9.4 Any type of oil cooler
2.9.5 Single ring piston and racing piston
2.10 Noise Control
Exhaust must have silencer. The noise limit will be 103db/A.There will be 3db/A
tolerance.
2.11 Change of Parts
Exchange of single parts or an assembly of motorcycle with those of the same
model bearing the same type of frame number and engine number is allowed.

rangkaian sein seperti mio

2010-11-25T14:30:00.001-08:00

bila ingin lampu sein motor anda seperti motor mio,buatlah rangkaian seperti diatas

battery test

2010-11-25T14:27:00.001-08:00

This schma for controled your voltage of your cars battery