Is it running rich… or lean?

Because if you guess wrong, you’ll waste hours changing the wrong jet - and often make the problem worse.

After working on dirt bikes for over 15 years, I’ve found that this is where most riders get stuck.

The good news?

You can usually tell if your bike is rich or lean in just a few seconds - by how it sounds and feels.

In this guide, I’ll show you:

• The exact difference between rich and lean symptoms
• What each one sounds like
• A simple test to confirm it
• What to adjust first

Quick Answer: Rich vs Lean Dirt Bike Symptoms

• Lean = not enough fuel → hesitation, dying sound
• Rich = too much fuel → sputtering, blubbering

The easiest way to tell is:
👉 Lean bog feels like the engine is dying
👉 Rich bog feels like the engine is loaded up

This is one of the most common questions riders ask when their dirt bike starts bogging or running poorly.

Lean vs Rich (Side-by-Side Comparison)

What Does “Running Lean” Mean?

A lean condition means your engine is not getting enough fuel for the amount of air.

Lean dirt bike symptoms

• Bog or hesitation when opening throttle
• Engine feels like it’s dying
• “Bwaaaahhh” sound
• Worse when snapping throttle
• Hanging idle (RPM stays high before dropping)
• Engine runs hotter than normal

This is one of the most common problems I see on bikes that have been sitting or have a partially clogged pilot jet.

What a lean bog sounds like

“Bwaaaahhh…”

👉 It sounds like the engine is losing power instantly

Other ways I describe it:

• It sounds and feels like you're hitting the kill switch
• Generally, the quicker you open the throttle, the worse it bogs when it's lean

What Does “Running Rich” Mean?

A rich condition means your engine is getting too much fuel, not enough air, or both.

Rich dirt bike symptoms

• Sputtering or blubbering
• “Brapapapap…” sound
• Feels sluggish or heavy
• Loads up at low RPM
• Clears out after revving
• Fouls spark plugs more easily

What a rich bog sounds like

“Brapapapaptatpa…”

👉 It sounds like the engine is struggling to burn excess fuel (drowning or "spitting")

Other ways to describe it:

• A false "rev limiter" - slightly less consistent and at a lower RPM
• "4-stroking" on a 2-stroke (like when you leave the choke on for too long)
• "8-stroking" on a 4-stroke

Real Examples (From Bikes I’ve Fixed)

Here are a few real-world cases:

• KTM 150 XCW - lean bog that looked rich (very common mistake)
• CRF230F - lean off-idle hesitation fixed with a larger pilot jet
• KDX220 - rich bog caused by internal carb issue

This is why diagnosing FIRST is more important than changing parts.

The Fastest Way To Tell (My “Sounds & Symptoms” Method)

This is the same method I use on every bike I work on:

Step 1 - Listen

• Lean → dying / flat sound
• Rich → sputtering / blubbering

Step 2 - Feel

• Lean → hesitation, no power
• Rich → sluggish, loading up (may clear out)

Step 3 - Throttle test

• Gets worse when you snap throttle → lean
• Gets worse under load or low RPM → rich

PRO TIP: I like to do this throttle test in a higher gear (3rd or 4th) and ride up a slight incline (deep sand also works) to put a "heavier load" on the engine. This makes the engine work harder and the symptom will be more pronounced, making it easier to recognize.

The Choke Test (Quick Confirmation)

This is one of the fastest ways to confirm:

• Runs better with choke ON → too lean
• Runs worse with choke ON → too rich

Where Each Problem Happens (Throttle Position)

👉 This is how you pinpoint the exact problem quickly

Common Mistakes Riders Make

• Thinking every bog is lean
• Changing the main jet first
• Ignoring throttle position
• Guessing instead of testing

What To Adjust First

If your bike is running lean:

• Increase fuel (bigger jet or adjust/fuel screw)

If that helps but not enough, I recommend checking for a dirty pilot jet/carb passages or an air leak. Most dirt bikes I buy that have sat for months or years have dirty jets/carb circuits, causing it to run lean.

If your bike is running rich:

• Reduce fuel (smaller jet or adjust screw)

If that helps but not enough, I recommend checking for blockage before and after the engine. A dirty air filter or clogged exhaust will make it run rich.

When This Matters Most

If your bike:

• Bogs off idle
• Hesitates when accelerating
• Feels inconsistent

👉 This is usually where riders misdiagnose the problem

Is your dirt bike bogging when accelerating?

If your bike bogs specifically when taking off:

👉 Read this next: Dirt Bike Bogs Off Idle (Step-by-Step Fix for Hesitation)

For full diagnosis:

👉 Read: Dirt Bike Bogging: How To Diagnose Rich vs Lean Bog Step-By-Step

Frequently Asked Questions

Your Next Step

Now that you know whether your bike is rich or lean…

👉 Start with your air/fuel screw.

It’s the fastest way to diagnose your pilot circuit.

👉 Get my Air Screw (2 stroke) Guide
👉 Get my Fuel Screw (4 stroke) Guide

The good news?

This type of bog is usually easy to diagnose - and often quick to fix.

In most cases, it comes down to the pilot circuit, which controls the jetting from 0 to roughly ¼-turn throttle (or idle to low RPM).

After working on dirt bikes for over 15 years, I’ve found that riders almost always misdiagnose this problem at first - usually chasing the wrong jet or making changes that don’t fix anything.

In this guide, I’ll show you:

• What causes bogging off idle
• How to tell if it’s rich or lean
• The exact steps to fix it quickly

Why is it bogging right off idle? (Quick Answer)

If your dirt bike bogs off idle, the most common causes are:

• Pilot jet issues
• Incorrect air/fuel screw adjustment
• Lean air-fuel mixture
• Dirty carburetor

The fastest way to fix it is to focus on the pilot circuit, because that controls throttle from 0 to ¼.

If your bike hesitates, dies, or feels weak when you first take off, this guide will show you exactly how to diagnose and fix it step-by-step.

What Does “Bogs Off Idle” Mean?

Bogging off idle happens when the engine struggles right when you start to accelerate.

Common symptoms

• Hesitates when you take off
• Dies when you give it throttle
• Feels weak or delayed
• Hard to ride smoothly at low speed - feels like "jerky throttle"

What Causes A Dirt Bike To Bog Off Idle?

The most common causes are:

1. Pilot jet is too small [or clogged]

• Many 4 stroke trail bikes come jetted too lean from the factory (to reduce emissions)
• Pilot clogs up often after sitting

2. Air screw / fuel screw is out of adjustment

• Too lean = hesitation
• Too rich = sluggish response

Before jumping to changing pilot jet sizes, you can easily adjust the air screw (2 stroke) or fuel screw (4 stroke) to know if you already have the right size pilot jet, or if it's too big/small.

3. Accelerator pump not working properly (Some 4-stroke carbs)

• Not enough fuel at low throttle
• Causes hesitation or dying

I've seen a lot of accelerator pumps fail on Keihin FCR carburetors, which come stock on the first years of 4 stroke Motocross bikes before they went to fuel injection, such as the 2004-2009 Honda CRF250R.

4. Dirty carburetor

• Especially the pilot circuit passages

This is one of the most common issues I see on bikes that have been sitting…
All it takes is one spec of dirt or "crud" to cause bogging or jetting issues. It's usually caused by bad gas - pump gas that has sat for months or years.

5. Air leak

• Extra air makes it run lean
• Causes inconsistent idle and hesitation

👉 Read full guide: Dirt Bike Air Leak Symptoms (Coming soon!)

How to find an air leak in seconds

The easiest method for finding air leaks that I have found is spraying brake cleaner (Amazon) around all areas of the carb and intake while the engine is idling - because it's flammable. If the idle RPM changes when you spray the brake cleaner, there's likely an air leak.

How To Tell If It’s Rich Or Lean (Quick Test)

This is where many riders get confused and waste hours or days going the WRONG direction.
I've discovered a simple method based on "sounds & symptoms" to tell the difference between rich and lean symptoms, and it's worked on every 2 stroke and 4 stroke dirt bike I've diagnosed and tuned.

Lean bog (most common)

• “Brraaaauhhh” sound
• Feels like the engine is dying (like you're pressing the "kill switch")
• Worse when snapping the throttle open quicker

Rich bog

• Sputtering or blubbering
• Feels "loaded up"
• May clear out after revving
• Sounds like a "rev limiter" but less consistent and at a lower RPM

Quick Diagnosis Shortcut

• Bog when taking off → pilot circuit
• Gets worse with quick throttle → likely lean
• Sputters and loads up → likely rich

Quick choke test (easy win)

Turn the choke ON briefly:

• Runs better → too lean
• Runs worse → too rich

Step-By-Step Fix (Start Here)

Step 1 - Adjust air/fuel screw

This is the fastest and easiest fix.

• Turn in/out in small increments
• Find strongest idle + smooth throttle

👉 This alone fixes MANY bikes

Step 2 - Clean the pilot jet

If adjusting didn’t fix it:

• Remove or rotate carb
• Clean pilot jet thoroughly
• Blow out passages

PRO TIP: If you only need to clean the pilot jet, I prefer to loosen the carb clamps, rotate the carb so I can remove the float bowl or drain plug to access the pilot jet.

Do NOT spray carb cleaner into the carburetor!

A common mistake for cleaning a dirty carb is just spraying carb cleaner (Amazon) into the carb/jets/passages, but this will RUIN the gaskets and seals.

If you need to clean the entire carb, I highly recommend removing all of the jets and seals/gaskets before using an aggressive cleaner, or else the rubber/paper materials will soak up the cleaner and fall apart and clog passages or "swell" up.

Step 3 - Test pilot jet size

If still bogging:

• Lean bog → go bigger
• Rich bog → go smaller

If the symptom is almost gone after tuning the air/fuel screw, I only go one size bigger or smaller on the pilot jet (ie, 42 to 40, or 42 to 45).
If it's bogging badly, I sometimes go two sizes (ie, 42 to 48)

How do pilot jet sizes work?

Keihin carburetor pilot jet sizing chart (there are more sizes, but these are the most common when I tune dirt bike carbs):

• 35 (smallest = leanest)
• 38
• 40
• 42
• 45
• 48
• 50 (biggest = richest)

Mikuni carburetor jets work the same way; they just use different size numbers (ie, 12.5, 15, 17.5, etc.)

Step 4 - Check for air leaks

• Intake boot
• Carb clamps
• Reeds (2-stroke)

Intake boots often crack after old age due to the rubber getting hard and flexing so much.

Common Mistakes To Avoid

• Changing main jet first
• Guessing rich vs lean
• Ignoring pilot circuit
• Adjusting too many things at once

When It’s NOT The Pilot Circuit

If your bike:

• Runs fine off idle
• But bogs at mid or high throttle

👉 It’s likely:

• Needle
• Main jet

👉 Go back to the full guide: Dirt Bike Bogging (Step-by-Step Diagnosis)

Frequently Asked Questions

Your Next Step

If your bike still feels:

• Hard to control
• Jerky off idle
• Inconsistent

Start with the air/fuel screw.

It’s the fastest way to tell if your pilot circuit is correct.

👉 Get my Air Screw Tuning Guide here [2-stroke]
👉 Get my Fuel Screw Tuning Guide here [4-stroke]

You’re not alone - and the good news is most bikes don’t need anything major to run again. In fact, the majority of “non-running” dirt bikes just need a few simple fixes done in the right order.

In this guide, I’ll show you exactly how to bring a dirt bike back to life step-by-step - even if you’re a beginner.

👉 Watch the full process here:

⚠️ WHY DIRT BIKES WON’T START AFTER SITTING

When a dirt bike sits for months or years, a few common things happen:

• Fuel goes bad and turns into varnish
• The carburetor gets clogged
• The air filter gets dirty or restricted
• Oil breaks down and loses protection (less reliability!)

The key is not guessing - it’s checking the right things in the right order.

🛠️ STEP-BY-STEP: HOW TO GET IT RUNNING AGAIN RELIABLY

1. Drain the Old Fuel

Old gas is the #1 cause of starting issues.

• Drain the tank completely
• Refill with fresh fuel
• Check fuel lines if needed

👉 If you skip this, nothing else matters.
In the video, my XR50 not only had bad (old) gas, but the fuel system itself was compromised.
I had to:

• Open up the gas tank
• Remove & inspect the petcock (the inner filter had disintegrated!)
• Replace the petcock & fuel line (PRO TIP: Install an inline fuel filter to help avoid dirty carb problems!)

2. Clean the Carburetor (Most Important Step)

If your bike still won’t start, this is usually the problem.

• Remove the carb
• Disassemble and clean jets and passages
• Reinstall or rebuild if needed

👉 This is where most people get stuck or do it wrong. Do NOT just pull the float bowl off and use "carb cleaner spray" in the jets/passages. Carb cleaner will RUIN the rubber seals and paper gaskets, making your bike run worse than before, if at all!

This is why I always use ethanol-free gas in my dirt bikes and small engines, whenever possible. Ethanol attracts moisture, breaks down in a matter of weeks or days, and clogs up small jets.

If you don't have access to ethanol-free fuel, I highly recommend treating your gas with Ethanol Shield (Amazon). From the tests I've seen, it works much better than traditional "fuel stabilizers". I've never used stabilizers anyway and don't remember the last time I've had a problem (even storing a bike for 6-12 months up here in Minnesota.

3. Change the Oil

A big reliability mistake is not checking or changing the oil and oil filter. A dirt bike that's been sitting for a while may have been neglected, and the oil is likely dirt and/or low = more wear and tear on the first start-up of the engine.

• Old oil = poor lubrication
• Quick and cheap insurance

Even if it looks “okay,” don’t skip this right after you get the bike running again. In my video above, the oil was still full and clean on my XR50, so I didn't change it before starting it, but I will soon after making sure it runs right.
With that said, if the oil is low (on the dipstick or sightglass), or it's black/sludgy, these are signs to change it NOW before it wears out your engine quickly, forcing you to rebuild it sooner than later.

4. Clean or Replace the Air Filter

A clogged air filter can choke the engine. I've seen many things clogging an air filter, such as dirt and mud, leaves, or a mouse nest of seeds, garbage, or foam (they ate part of the filter!).

• Clean + re-oil OR replace
• Make sure airflow is good

Beginner Mistake: Not properly oiling the air filter. A dry (not oiled) air filter is fine for riding on the street, but I would NOT do that in the dirt because it will suck in more dirt and debris, killing your engine in no time!

A properly oiled air filter is completely covered on both sides 9with "air filter" oil), but if you can gently "squeeze" oil out of it, there's too much - this will make it run "rich" because not enough air can get through, similar to a dirty air filter blocking the air.

❌ COMMON MISTAKES TO AVOID

1. Jumping Straight to the Carb

Most people tear the carb apart first…

👉 When the real problem is just old fuel.

2. Not Cleaning Jets Thoroughly

A quick spray isn’t enough.

👉 You need to fully clear blockages.

3. Skipping the Air Filter

This can cause poor running even if everything else is correct.

4. Trying to Start It Repeatedly Without Fixing the Problem

This can flood the engine and make things worse.

5. Ignoring Reliability After It Starts

Getting it running is step one.

👉 Keeping it running reliably is what matters.

WHAT TO DO NEXT IF IT STILL WON’T START

If you’ve done everything above and it still won’t run, the issue is usually:

• The carb/fuel system is still partially clogged
• Incorrect carb settings
• Spark, compression or ignition issue

👉 This is where most people start guessing - and wasting time.

FREE CHEAT SHEET (HIGH-CONVERTING CTA)

If you want a simple checklist that walks you through exactly what to check (in order), grab this:

👉 Dirt Bike Won’t Start Cheat Sheet [Tap Here]

It’ll help you:

• Diagnose faster
• Avoid unnecessary work
• Know exactly what to fix next

HOW TO KEEP YOUR DIRT BIKE RUNNING RELIABLY

Once it starts, don’t stop there.

To keep it running:

• Use fresh fuel
• Clean carb properly (not halfway)
• Maintain the air filter regularly
• Ride it consistently

👉 Most reliability problems come from neglect, not major issues.

Fixing your bike is step one…

But if you’re still struggling with:

• Stalling
• Lack of confidence
• Feeling out of control on trails

That’s not a bike problem - it’s a skill problem.

👉 That’s exactly what I help riders fix. I just made a 60-Minute Trail Confidence Breakthrough Ride, showing you some simple drills that will give you more confidence and control on your next ride. Grab it for free today!

NEXT STEPS

• Carb cleaning guide
• Dirt bike maintenance guide
• Trail riding confidence article

How long has your dirt bike been sitting?

And what’s it doing right now — not starting, bogging, or something else?

Drop a comment below 👇

Are you considering buying the new Honda CRF300F trail dirt bike but not sure if it's the right size or type of bike for you?

In this review, you'll learn what type of dirt bike the CRF 300F is, how to know if it's the right size bike based on your height and weight, as well as what to expect when riding and owning one.

What Is The Honda CRF300F?

The CRF300F is a 294cc air-cooled four-stroke trail bike. It's made for beginner or casual trail riders who want a low-maintenance dirt bike that's easy to ride.

Honda discontinued the CRF250F and introduced the CRF 300F as the newer model for 2026. I'll cover the differences later in this article.

CRF300F vs CRF300L (Totally Different Bikes!)

The CRF300L is a street-legal dual-sport bike from Honda, while the CRF300F is an off-road-only trail bike.
The 300L has a liquid-cooled and the 300F has an air-cooled engine.

Is Honda Going The WRONG Direction??

CRF300F Engine Characteristics

Do you want "smooth" power? If you want "enough" but not "too much", this 300 may be just the ticket!
The difference between this engine and a "race bike" engine is that this air-cooled engine has good power right off of idle and steadily pulls all the way until it peaks. As opposed to a race engine that is very weak off idle, slowly builds in the midrange, and then seems to surge with an excessive amount of power on the top-end.

Upgrading from 250cc to 300cc, the CRF 300F should have noticeably more power at every RPM, especially if Honda updated the head/porting/etc to match the upgrade in displacement size.

From 5-speed to 6-speed transmission

Most riders won't tell a difference, but it's definitely a change from the previous CRF250F, which had 5 gears.

The 6-speed tranny on the new CRF 300F should be a nice upgrade to ride tight trails at low speed while still being able to cruise down gravel roads at a higher speed without winding the engine out.

Horsepower

A stock CRF250F makes about 20 HP at the rear wheel, so I'm guessing the CRF300F will be around 22 horsepower (which would be about 25-26 HP at the crank).

CRF300F Weight

The biggest drawback of the CRF300F, besides the suspension, is the weight. The XR200 was fairly lightweight, but the next-gen CRF230F got heavier (mainly due to the electric start), and then the CRF250F gained even more weight (about 16 lbs.). 

At 273 pounds, the CRF300F is still not super noticeable for casual trail riding because the center of gravity is much lower than taller enduro bikes. But you’ll notice the weight if you need to pick it up off the ground.

Seat height - is it the right size for you?

The CRF300F seat height is 35.0 inches, which is about 3 inches lower than a typical enduro bike. This gives newer or shorter riders more confidence because you can touch the ground more easily.

Even though it's heavier than most race bikes, the CRF300F is still a great beginner bike if you’re over 5'6" tall and want a full-size bike (21/18" wheels). If you’re a short beginner rider, you might want to consider something like the KLX140L, CRF125F, or TTR125.

Honda CRF300F Specs & Dimensions

These are the specifications according to Honda:

Is the CRF300F street legal?

No, the CRF 300F does not come street legal from the factory. It doesn’t have any lights, horn, DOT tires, or other equipment needed to be legal to ride on the road.

With that said, some states may allow you to register it for road riding with the proper modifications to make it legal.

*Is the CRF300F good for dual sport riding?

From the factory, it's not a great motorcycle for dual sport riding because it has off-road only tires, no lights/street equipment, and the gearing is too low.

It's also underpowered for longterm highway riding, and it’s not the most comfortable to sit on for hours at a time. The CRF250L/300L would be a much better dual sport bike.

CRF300F Price - new or used?

Keeping the same price as the 250cc predecessor, the new CRF300F price (MSRP) is $4,999 in the United States.
With that said, the "OTD price" varies depending on your local dealer and the fees they may or may not charge.

Is a CRF300F a good beginner bike?

The CRF 300F is a great beginner bike if you're an adult or teen who is the right size for this bike. The biggest drawback is the weight of this 300cc trail bike. It can be hard to handle if you're a small or not very strong.

With that said, it's very easy to ride because the power is smooth and predictable, and the suspension is plush and comfortable for riding at low speeds under 20 mph.

CRF300F Pros:

• Very easy to ride for teens & adults
• Super reliable
• Good handling at low speeds & in the woods - weight isn't that noticeable
• Electric start & fuel injection reduce a lot of frustration
• Has potential if you're willing to upgrade the suspension
• Power is not a problem - especially if you seek out the right mods
• Affordable compared to enduro bikes
• Simple & easy to maintain

CRF300F Cons:

• It's a little bit heavy when you drop it
• The suspension is not adjustable, which is lacking for a hardcore/experienced trail rider

FREE Size Chart - Still Unsure?

If you're still not sure what size dirt bike is best based on your height and weight, I made a free size chart that you can grab here for free!

That's why I put together this article & video that will show you:

• The 12 best dirt bike upgrades for trail riding that will give you more comfort, confidence, and protection for your or your dirt bike
• Why each mod actually works
• Bonus tip that will build your confidence more than any of the previous 12 mods

Aftermarket parts (our Amazon affiliate links if you wish to support us - thank you!):

Exhaust Pipe Dents - Pipe Guard

If you ride on rocky terrain or you fall over often, it doesn’t take much to smash up your pipe, even a smaller 4 stroke head-pipe!

Adding a simple pipe guard will help prevent dents as well as severe damage to your headpipe/expansion chamber, depending on the type you get.

• 2-Stroke Armadillo Pipe Guard (Amazon)
• 2-Stroke Carbon Fiber Pipe Guard (Amazon)
• 2-Stroke Cage Pipe Guard (Amazon)
• 2-Stroke Skid Plate With Pipe Guard (Amazon)
• 4-Stroke Aluminum Pipe Guard (Amazon)
• 4-Stroke Universal Exhaust Heat Protector (Amazon) - doesn’t do much for rocks/roost, but protects your leg/boot

Don’t Run Out of Gas! - Auxiliary Fuel Tank

Whether you’re heavy on the throttle, have a small gas tank, or you put a lot of miles on, a dirt bike never feels heavier than when it runs out of gas…

You could fill up some used pop bottles of gas, but if you don’t want to carry them in a backpack, there are some options to bring an extra few ounces to another gallon or more!

Larger fuel tank (Amazon)

• Requires switching out OEM gas tank/petcock
• Most convenient
• 0.5 to 1.5 extra gallons of fuel (varies by model/tank)
• May interfere with aftermarket radiator guards/larger radiators
• Most expensive ($200-400)

Aux fuel bottle (Amazon)

• Can be mounted in different locations (fender/plate/rack)
• Least amount of extra fuel (11-30 oz. per bottle)
• Least expensive ($20-30 per bottle + mount)

Aux front number plate tank (Amazon)

• Replaces the stock front plate or headlight
• 0.8 Gallons
• Siphons directly to the stock tank (no stopping) and is used first
• May interfere with the steering stabilizer (some Honda’s)
• Moderately expensive ($100-150)

Aux handlebar tank (Amazon)

• Mounts on top of handlebars (most “top heavy” out of all options)
• 0.55 gallons
• Siphons directly to the stock tank (no stopping) and is used first
• Works with ⅞” & 1-⅛” bars
• Moderately expensive ($100-150)

Aux fender tank (Amazon)

• Typically mounted on rear fender (requires a strong fender or rack)
• 1.6 gallons (about 10 lbs when full of fuel)
• Siphons directly to the stock tank (no stopping) and is used first
• Moderately expensive ($100-150)

Catch Your Spewing Coolant - Coolant Tank

Leaking a little bit of coolant out the overflow isn’t a big issue, but if you’re constantly spewing coolant out because you ride tight and technical trails, slipping the clutch, and heating up the engine, it’s going to get hotter longer.

If your bike loses too much coolant, it will eventually overheat and damage and seize your engine!

Adding a simple coolant recovery tank (Amazon) is affordable and effective because all of the coolant that gets pushed out of the radiator is “caught” in this lightweight plastic tank. 

So, you save time by not having to keep refilling the radiators and money by not buying more coolant or building your expensive engine!

Stop Getting Flats - Tube Upgrade

A flat tire (tube) can ruin your day of riding, especially when you’re just 2 miles in and you didn’t bring a spare or tools to change it! Most “pinch flats” happen from hitting a sharp rock or object at high speed (or jumping), causing the tube to compress and “pinch” against the rim or tire, making a tiny hole or tear that leaks air.

A cheap way to prevent 90% of pinch flats is by going to thicker tube. Most stock tubes are 1.0-1.5mm thick, but a heavy duty tube can be 2-3mm or even thicker.

Here are 3mm heavy duty tubes for full-size dirt bikes:

• 80/100-21 (Amazon) - Front tube for full-size dirt bikes w/ 21” front wheel
• 110/100-18 (Amazon) - Rear tube for full-size enduro/trail bikes w/ 18” rear wheel
• 100/90-19 (Amazon) - Rear tube for full-size motocross bikes with 19” rear wheel

More Traction AND Less Stalling - Flywheel Weight

Does your bike have “snappy” power, where it wheelies or spins the rear tire easily, especially on wet or slippery terrain? One of the easiest ways to make your bike more controllable is by adding a flywheel weight (Amazon).

It doesn’t affect torque or horsepower, but rather, “slows down” the engine. That may sound like a bad modification, but think about it.

If your engine feels snappy because it revs up too quickly, or it stalls easily because it revs back down to idle too quickly, adding extra flywheel weight will slow down the acceleration and deceleration.

It won’t be a huge change, but enough to help the rear tire “hook up” for better traction and prevent unwanted wheelspin or excessive acceleration.

It will also help reduce stalling because it’s slower to rev back down. In most cases, it attaches to the stock flywheel and can be easily removed later if needed.

Better Power With LESS Annoyance - Exhaust For Trail Riding

Some stock exhaust systems are restrictive, but some are simply illegal for trail riding. For example, here in the U.S.A., a U.S.F.S. approved spark arrestor is required to ride on state trails to help prevent sparks from shooting out of the muffler and starting a fire.

If you have a race bike, installing an aftermarket muffler with a spark arrestor will usually help quiet it down (less likely to annoy others, leading to less noise complaints and shutting trails down). It may slightly reduce power, but that’s a sacrifice you’ll have to take.

If you have a 2 stroke, adding an aftermarket silencer with a spark arrestor, such as the FMF turbinecore (Amazon) is an easy way to reduce noise, while producing good power and riding legally.

Don’t DESTROY Your Frame & Engine Cases! - Skid Plate

If you ride in tight or technical terrain, you’re bound to smash into rocks or logs, which can break your bike. It only takes one tip over to dent your frame, or worse - crack your expensive engine case!

Adding a skid plate is an easy way to add insurance because it can prevent a lot of damage. There are quite a few options to choose from, so pick the one that makes the most sense to you.

For example, you can typically choose between plastic and aluminum, and then the amount of coverage each skid plate offers. Plastic is lighter and quieter, but not as durable.

If you plan on smashing into a lot of rocks, you might want to go with a stronger aluminum skid plate.

SEE Where You’re Going At Dusk! - Headlight

Have you ever been stuck out changing a tube when the sun is setting while you’re on top of a mountain peak and you have 10+ miles to ride to get back to camp?

Yeah, it’s kind of hard to see when the sun drops below the mountains and you have poor or no lighting. Also very scary riding mountainous terrain! Adding a cheap headlamp to your helmet or handlebars is an easy way to make it relatively safe.

Here are 3 practical options:

• Handlebar headlamp rechargeable (Amazon) - Cheap, mounts to bars
• Helmet light rechargeable (Amazon) - Comes with a strap or use industrial velcro
• Headlight LED (Amazon) - May requiring wiring/stator upgrade depending on your bike

Protect Those Digits From Trees & Branches! Hand Guards

If you’ve ever smashed your hand on a branch, let alone a solid tree, you know how much it hurts! Adding some hand guards is a great modification for trail riding, especially if you ride in the woods often, but there are a few options to choose from:

• Open MX “Flag” Type Plastic Mount (Amazon) - Cheap, easy to install, protects from roost and small branches, but bends easily
• Open-end Metal Mountplastic “  (Amazon) - Cheap, easy to install, protects from roost and small branches, slightly stronger than MX guards
• ⅞” Aluminum “wraparound” guards (Amazon) - Strongest, prevents broken levers, adds 1” width to bars, increases bar rigidity
• 1-⅛” Aluminum “wraparound” guards (Amazon) - Same as above but for 1-⅛” bars (fatbars)

Better Control From Better Traction - Tires

3 Common mistakes that KILL your traction, which lead to less confidence because you’re more likely to slide out:

1. Using 15+ PSI tire pressure (to prevent flats)
2. Riding on 5+ year old tires (even if the knobs are still long)
3. Using the wrong type of tire for your terrain

More than 15 lbs of pressure riding off-road is excessive and will reduce the amount of traction you have, causing your front and rear tires to slide out more easily (scary!).

Lowering the PSI down to 12-14 PSI with standard tubes will allow the tires to compress and flex more, giving you better traction because the “knobbies” will dig into and grab the terrain better.

Here are the 3 main types of dirt bike tires based on the terrain you ride:

• Soft Terrain = Sand, soft dirt, or mud
• Intermediate Terrain = mixture of soft and hard dirt/terrain
• Hard Terrain = Hardpack/clay/rocks

Here are 2 different sets of tires from Tusk:

• Soft/Intermediate terrain 21/18” tires (Amazon)
• Intermediate/Hard terrain 21/18” tires (Amazon)

Easy Starting & Smooth Throttle Response

Does your dirt bike take 5+ kicks to start cold and 3+ kicks to start when hot? It’s even harder when you’re on the side of a steep hill, and it’s hard to balance when you have to kick it over (this is when electric start comes in handy!).

In any case, hard starting and poor throttle response (bogging, sputtering, hesitating) are common signs that the carburetor needs to be tuned (or EFI system if it has fuel injection).

The easiest and best place to start is the air/fuel screw because it controls idle to roughly ¼-turn throttle response, and you don’t even have to remove the carb to make an adjustment. I have a free guide on how to do it in just a few minutes, whether you have a 2 or 4-stroke:

• 2 stroke - FREE air screw tuning guide
• 4 stroke - FREE fuel screw tuning guide

How will I be able to stop or get back down without falling backward and the bike crashing on top of me?
These are legitimate fears that many of us trail riders have had at one point, or maybe you still do...

If that sounds like you, know there's a way to quickly improve your skills so that you can either get up the challenging steep hills or safely get back down if you stall out.

Some of the biggest mistakes that I see trail riders making that cause you to get stuck on an uphill section in the woods are:

• Looking down at the trail (just past your fender)
• Accelerating once you get to the uphill section
• Giving it gas but the tire is spinning, causing you to lose momentum/stop
• Riding in the highest RPM range
• Sitting towards the rear of the bike to get more traction

If you're making any one of these mistakes, there are some quick and easy ways to improve your skills and confidence so that you get up the hill with less effort.

If you've struggled to get up steep hills in the woods and you've tried to improve your skills, then I'm willing to bet that you've tried at least one of these:

• Just giving it more gas!
• Weighting the rear to prevent the tire from spinning
• Just going at it again and again, guessing at the right technique, hoping you'll reach the top next try
• Having your buddy always ride your bike up the steep hills

If you ride with other trail riders who seem to get up steep hills with little to no effort and are baffled because you don't know what you're doing wrong, this is a sign that you have lots of room for improvement (It's GOOD that you're noticing it now!)

The question is, are you going to keep trying to figure it out on your own, hoping that you'll improve by this time next year?

It's possible, but it takes a lot more seat time.

Do you have the time and patience to ride at least twice a week to improve?

What if you fall over on every steep uphill section and start breaking parts?

-$25 for a new clutch lever

-$95 for new handlebars and grips

-$295 for a new pipe that was smashed by a rock

Just "giving it more gas" is not the best way to get up steep hills.

Many trail riders try this, thinking that it will get him or her up a hill faster, which seems like a good idea, but it doesn't always help.

Why?

There's a few things that can go wrong if you're just twisting the throttle more:

1. If you're not paying attention to the terrain or have proper throttle control, it's easy to give it too much gas, causing the rear tire to spin.

Once the rear tire starts spinning, you're losing momentum, making it much harder to reach the top.

2. If you know the rear tire might spin, you might be "getting over the rear" of the bike while gassing it, but this can make you wheelie, forcing you to let off the gas or dumping you off the rear (and hopefully not flying down the hill!)

3. Or if you're twisting the throttle and "hoping for the best", you're more likely to fly off the trail, which could end up hitting a tree or sliding down a ledge cliff - scary!

Getting proper traction is key to getting up steep hills, especially when the terrain is slippery.

It requires proper body position, throttle control, as well as knowing what's coming up on the trail.

Uphills "Made Easy" - Discover all of the best techniques today!

If you'd like to start mastering uphills in the woods today, rather than taking months or years trying to figure it out on your own, I highly encourage grab my new "Uphills Made Easy" troubleshooting workbook.

I want YOU to have more confidence, but ultimately I want you to stay safe and have more fun, and that's what this practical workbook is designed to do - get you results in the SHORTEST time possible (just minutes of reading and then applying it)

Click here to grab it now at this introductory price before it's too late!

It's a PDF that can be viewed, downloaded, or printed out - share it with your spouse or kids!

How do you know if you can improve right now?

Here are 5 common symptoms that you’re still struggling with tight, sharp turns:

• You have to put a foot down at least 50% of the time when making a sharp turn
• You fall over on tight turns when you slow down or stop and can’t put a foot down because your bike is too tall or the ground is uneven
• You overshoot turns when they’re too tight (ride off the trail)
• You have to get off and turn the bike when other riders don’t
• You’re afraid of the bike because it feels tall and heavy

Do any of these sound like you?
If so, you haven’t mastered the basic technique of turning a dirt bike at low speeds.

And guess what?
You can learn how to do it with confidence in just a few minutes!

First, I need to cover the top mistakes I made and why I see other casual trail riders struggling with tight or sharp turns, whether it be on the trail or in the open (these might be holding you back from having more confidence!)

Top Mistakes Trail Riders Make When Making Sharp Turns

Making a sharp turn on a dirt bike can be a challenge because it feels heavy and wants to fall over or slide out, but it’s easier than you might think - even if you have short legs and aren't strong (like me!)

When I see or help trail riders who are struggling to make a tight turn in the woods or out in the open, they’re usually making at least one of these common mistakes:

1. Sitting in the same spot - Shifting your body position very little or not at all when turning
2. Trying to keep up with faster riders - Riding over your comfort/skill level (too fast to stay in control)
3. Stabbing at the brake - tire washes out (especially the front)
4. Riding in the middle of the trail - Maybe scared to get out of the main line because you might crash off the trail
5. Leaning with the bike when turning - When the bike leans left, your body leans left with the bike, causing you to drop the bike or put a foot down to prevent falling

If you’ve made one of these, you’re at the “Nervous Trail Rider” stage because you haven't mastered the basic turning techniques at slow speeds.

But don’t worry because that’s where I started too!

When I rode some technical trails for the first time on my 2000 Honda CR80, I got intimidated by tight sections with lots of trees, especially when the turn was sloping up or down because I couldn’t easily reach the ground with my foot!

I didn’t want the bike to land on me, and picking the bike up after falling was exhausting!

Plus, I felt embarrassed when all my friends had to wait for me…

If that sounds anything like you, then I have some good news!

Making a sharp turn doesn’t have to be challenging or scary, even if the bike weighs twice as much as you!

After riding for 8 years only to find out that I wasn't a confident rider on single-track trails, I realized that just getting more seat time wasn’t making me a much better rider.

It helped, but it was taking WAY longer than I hoped.

After years of reading books, magazines, and articles, as well as watching countless videos (because I had more time than money), I discovered my riding technique was holding me back.

This has to do with your body position when turning, and I want to help you improve that this week!

How Trail Riders Can Take Sharp Turns Without Falling

Now I'm going to reveal what I believe is the #1 technique when making a tight turn so that you don’t fall over, even if you’re over 60 years old and don’t have the same balance as you used to!

One of the BIGGEST mistakes that I made on tight turns in the woods was leaning with the bike.

For example, let’s say you’re trying to make a tight left turn, so you turn and lean the bike left, but you also lean your body left WITH the bike.

This usually ends up with one of two results:

1. You lay the bike over and hit the ground or you catch yourself with your foot (if you can reach in time - hopefully you don’t hurt your knee from all the weight!)
2. One or both of your tires wash out and you either slam into the ground or overshoot the corner if you catch yourself in time

These happen because the direction of load on the tire changes when you start turning, which is extremely important when trail riding a dirt bike.

If you’re used to riding a street bike, they are more forgiving because you have virtually 100% traction on the pavement.

When riding in the dirt, your tires want to push and slide out the more you lean the bike.

And when you lean WITH the bike (your body is at the same angle as the bike), this makes your tires want to slide out even more, especially if the turn is flat or slippery.

It’s like hammering a nail into a piece of wood.
When you pound it straight into the wood, it’s pretty easy.
But when you try hammering the nail into the wood at an angle, even just a few degrees, it wants to slide out.

As a general rule, the same goes for riding a dirt bike as you lean it over.
So, what do you have to do instead?

The "Counterbalance" cornering technique for tight turns

I’ve found that counterbalancing my weight to be most effective on virtually any tight turn.

Honestly, I’m still testing and perfecting this technique, but it’s allowed me to ride faster in the woods because balancing is SO much easier, even when I’m 143 lbs and the bike weighs nearly 270 lbs!

What is this counterbalance technique?

When you turn and lean the bike left, you must keep your body upright (it will feel like you’re leaning the opposite direction at first).

This “counterbalances” the weight of the bike, making it easy to turn sharply without losing your balance, whether you’re riding a pit bike or a 500+ lb ADV bike.

This is just one of the many ways to improve your confidence and control when taking a sharp turn.

If you want to get my complete guide to master these techniques 5X faster than trying to figure it all out on your own, check out my Tight Turns Made Easy Troubleshooting Guide.

In this article and video, I'm going to break down:

• What a hanging idle actually is
• What happens if you DON'T get it fixed
• What causes a hanging idle
• How to fix it based on specific problems your bike is having

What is a “hanging idle” on a dirt bike?

It's when you rev the engine by twisting the throttle, and when you let off the gas, the RPM stays high and takes longer to “settle down” to a normal idle RPM. 

Even when you completely let go of the throttle, it takes an extra 1-5 seconds more for the rpm to stabilize.

What will happen if you don't fix a hanging idle

Not only is it frustrating having to wait for the engine to settle down to a proper idle RPM, but it can also be dangerous for you and your bike. 

If you're riding and the RPM “hangs” when you let off the gas, it's going to keep accelerating, potentially causing you to fly off course or hit a tree in the woods. 

The engine will also run hotter and can potentially seize, depending on the cause of the hanging idle, which I'll cover next. 

What causes a hanging idle?

There are many possible things, such as an air leak, incorrect jetting, or throttle cable problems. The main cause of a hanging idle on a dirt bike is that there is too much air getting to the engine.

Think of it like the throttle being stuck open, making the engine rev higher, but then there's not enough fuel to keep the engine cool, which is why it will typically run hotter. 

Is a hanging idle rich or lean?

In virtually every case that I've had, a hanging idle has been caused by an air-fuel mixture that's too lean. 

That's not to say that the jetting isn't too rich, but being too rich typically doesn't make it have an idle that won't drop/settle down. 

How to fix a hanging idle

First, you need to troubleshoot if there's an air leak, a throttle issue, or a carb jetting problem. Always start with the easiest things first 

Below is a list of all the common causes for a dirt bike hanging idle that I've had to troubleshoot, diagnose and fix over the years. Many of them can happen on a 2 stroke or 4 stroke dirt bike, but I've found that it's more common on a 4 stroke motocross bike, such as a CRF250R because more things can cause it. 

Idle set too high

The easiest thing to check is the idle adjustment screw. The idle RPM changes as the engine warms up, so if it was set when the engine was cold/not fully warmed up, it may cause a hanging or high idle when the engine is hot. 

The idle screw is usually on the left side of the carburetor/throttle body and can be adjusted by finger or a screwdriver. Turning it out (CCW) will lower the idle RPM. 

Air leak around the carb

When the carburetor isn't properly sealed, air can leak around it, causing the air-fuel mixture to be too lean (too much air), resulting in a hanging idle. 

Make sure that the air boot and intake manifold are properly fitted all the way around the bells of the carb and that the clamps are tight. 

For carbs that are bolted to the intake manifold, make sure the nuts are snug, as well as the o-ring/gasket is in good shape and not cracked. 

Intake cracked

The intake manifold is the rubber piece that connects the carb to the engine. If it's cracked (common on bikes more than 10 years old because the rubber hardens and cracks over time), this will cause and air leak and a hanging idle condition. 

Replace the intake with a new one or a used one that's soft and flexible. 

Air/fuel screw too lean

The air/fuel screw adjusts the fuel mixture for the pilot jet circuit, which controls idle to roughly ¼ turn throttle openings. When it's not properly tuned, it can make your dirt bike engine run lean and have a hanging idle. 

¼ of a turn of the screw can make a fairly big difference in how it starts and runs. 

For a free guide on how to tune your air/fuel screw in just a few minutes, click the link below:

• 2-stroke air screw
• 4-stroke fuel screw

Air/fuel screw o-ring missing (if applicable)

The fuel screw on a 4 stroke carburetor should have a spring, washer, and a rubber o-ring installed on it in that order. If that o-ring is cracked or missing, it will cause an air leak that can make the idle hang because there's too much air getting through the carb. 

Simply remove the fuel screw and replace it. Pay careful attention when removing and installing because the o-ring can get caught or stuck very easily. 

The air screw on a 2 stroke carb may or may not have the rubber o-ring. If your bike is using the OEM carburetor, you can look up the parts fiche/diagram for your specific make/model/year to see if there should be one there. 

Dirty carb

When gas sits in a carburetor (especially pump gas with ethanol), it breaks down and can clog or “gum up” the jet circuits. The first one to stop working properly is usually the pilot jet because it's the smallest, and that's when you get that hanging idle problem. It's usually hard to start as well because it's not getting enough fuel. 

The easiest solution is to just replace the pilot jet with a new one (it only takes a tiny amount of crud to affect the jetting). 

I prefer to try and clean the jets to save money.
I use an ultrasonic cleaner, which I show you how to use to clean a carb step by step here. 

Pro Tips: How to prevent your dirt bike carburetor from getting dirty again:

• Use gas with 0% ethanol (gas without ethanol lasts longer because it doesn't absorb water and break down as quickly)
• Ride your bike at least once per month (to keep fresh fuel running through it)
• Don't use carb cleaner sprays (they ruin the rubber gaskets/o-rings)

Incorrect Pilot jet

If the pilot jet is clean and you've already tried richening the mixture screw (once you get past 2.5 turns out, it's a sign that you need a different size pilot jet), then you might just need a larger pilot jet. 

Hot start

Most liquid cooler 4 stroke dirt bikes have a hot start knob on the carb or lever on the left side of the handlebars that makes it easier to kick start when the engine is hot. 

A hot start problem arises when the hot start:

• Hot start lever doesn't have any slack (cable adjustment on the clutch perch)
• Threads get stripped on the screw going into the carb body (they're made of plastic)
• The o-ring/gasket cracked or is missing
• The plunger going into the carb corrodes and gets stuck open

Float height

The carburetor float controls the fuel level for all of the jet circuits. If the float height is set too low, the jetting will be lean all across the board, which can cause a hanging idle and a number of other problems, such as hard starting when cold and bogging. 

It doesn't take much to bump the float level off of the proper level, so check out this article on how to check and adjust the float. 

Throttle sticking

Sometimes it's not an air leak or jetting problem and it's just your throttle sticking open. A dirt bike throttle can be sticky from:

• The throttle tube is dirty from tipping over and getting dirt stuck on the bar, 
• The cable is old and corroded
• The slide/plate in the carb being worn or moisture on it (the chrome plating wears off after so many hours)

To fix these problems, you must:

• Clean the handlebar and throttle tube (or replace if broken) and replace the torn grip so dirt doesn't get in there again
• Lube and/or replace the throttle cable
• Clean or replace the throttle slide 

FCR mid-body gasket

The Keihin FCR MX carburetor is a good performing carb when properly tuned, but old age and bad gas or harsh carb cleaner chemicals can wreak havoc when trying to troubleshoot a “jetting” problem on a 4 stroke MX dirt bike. 

If you've tried every jetting change, or the pilot jet needs to be way bigger than stock to start and not have a hanging idle, there's a good chance the mid-body gasket needs to be replaced. 

A bad mid-body gasket on an FCR carb can cause a hanging idle, hard starting, bogging, and the accelerator pump not working. It's fairly easy to replace if you know how to take the float bowl and jets out. Just be aware that “no name” brand kits often don't fit properly, and it's a very specialized gasket. 

4 stroke valves worn/need adjustment

Intake and exhaust valves that are worn and/or out of adjustment can cause a hanging idle. 

The valve clearances typically get tighter as the valves wear, and eventually, they will leave the valves open at all times, causing an air leak and lack of compression. If your 4 stroke dirt bike has been getting harder and harder to start over time, it's likely the valves that need to be adjusted or replaced. 

Exhaust leak

When the exhaust isn't properly sealed at the mating points, it will cause a leak that can result in a hanging idle as well as a dirt bike that backfires.

These are common causes of an exhaust leak:

• Head pipe gasket damaged or missing
• Exhaust pipe is bent and not properly seated
• Pipe or muffler is cracked or has a hole 
• Head pipe to mid pipe or muffler 

Bottom Line

Start with the easiest things first so you don't waste your time. After you get it fixed, let us know what your problem was to help others like you get their bike running well!

Just to recap, here are the most common causes of a dirt bike hanging idle:

• Idle too high
• Air leak
• Intake cracked
• Air/fuel screw too lean
• Air/fuel screw o-ring missing
• Dirty carb
• Incorrect Pilot jet
• Hot start not working properly
• Incorrect float height
• Throttle sticking
• Mid-body gasket (FCR carb)
• Valves worn/out of adjustment (4-strokes)
• Exhaust leak

However, there is a time and place to use race fuel because it can do good things for your dirt bike. That’s why I’m going to answer the most common questions about race gas vs pump gas and how to know which is best for your dirt bike based on your specific needs.

Can you run race gas in your dirt bike?

Yep, you sure can… But it may not help. In fact, you may be doing more harm than good WHILE spending boatloads of your hard-earned money for nothing!

Why is race gas bad to run in a dirt bike?

If you're running race gas through a dirt bike that doesn't need it or isn't tuned for it, you might run into these symptoms/problems:

• Poor throttle response
• Spark plug fouling
• Less power

What fuel is best for dirt bikes?

The best fuel for your specific dirt bike is what the manual recommends. For example, a Honda CRF250F trail bike is made to work well with regular 87-octane pump gas.

Do dirt bikes need premium gas?

Dirt bikes with “race engines”, such as the Yamaha YZ250F motocross bike, require 91-octane premium pump gas.

The main difference is that most motocross or high-performance enduro bike engines have higher compression and need a higher octane to prevent detonation.

What happens if you use regular 87 in a dirt bike that requires 91 premium gas?

You may or may not notice the effects right away, but if you use the wrong gas or too low of octane for your dirt bike, the fuel will burn too quickly and potentially cause:

• Overheating
• Detonation
• More rapid fuel consumption
• Backfiring
• Bogging
• The top-end to burn down (wear out much quicker)

Does elevation affect what fuel you should use?

Yes, as you go up in elevation, there is less oxygen in the air, which means that the compression of your engine is lower. For example, if your dirt bike engine has a 13.5:1 compression ratio at 1000 ft. elevation, when you ride at 5000 ft. elevation the compression ratio might be closer to 12.5:1. 

I don’t have a calculator for this, but if you’re riding above 5000 feet elevation, you can generally run fuel with an octane rating that’s 2 full points lower than if you were riding closer to sea level (i.e. 91 down to 89)

Summer vs Winter pump gas

Another thing to keep in mind if you’re using pump gas is that it changes to a different blend in the winter (colder months) compared to the summer. The “winter blend” has extra additives that cause the fuel to break down quicker and “gum up” your carb/fuel system because it attracts more water.

What gas do pro motocross riders use?

Race fuels have changed a lot in the past 20 years because things were less complicated due to fewer regulations. VP110 leaded race fuel was common, but after doing some research, here’s what I found to be popular for pro motocross riders:

• VP Racing MR Pro6-HT Reg
• ETS Racing Fuels US MX 21 K2
• VP Racing MRX02 - 2 stroke 

Does race gas make a difference? VP 110 vs 93 Pump gas

Race gas, such as VP110, can make a positive difference in your dirt bike if it’s set up for it, especially if you’re racing and demand the most performance out of your engine.

Race gas will make more of a difference in your dirt bike if you:

• Have a higher compression engine (13.5+:1 in race bikes or 11.0+:1 in air-cooled engines
• Tune the carb or EFI system specifically for the race gas you’re using
• Care about consistency in peak power and throttle response

Race gas will NOT make a difference if you:

• Have a stock dirt bike
• Upgraded the intake and/or exhaust and nothing else
• Don’t tune the fuel system for the race gas that you’re using

How much HP does 110 octane add?

If you’re just using 110 octane gas for the reason of adding more power, you’re probably not going to feel or see any horsepower increase on the dyno. This is because octane doesn’t affect the power in itself.

However, if the 110 fuel has other additives that burn more efficiently and you properly tune the carb or EFI for it, then you could realistically see anywhere from 0.5 HP to 2.0 HP increase in performance.

Can you run 100 octane in a dirt bike?

Yes, 100 octane can be used in a dirt bike, but it’s most likely not the best unless it’s tuned specifically for it. Take 100LL aviation gas (Avgas) for example - it’s an easy way to run higher octane fuel if your dirt bike has higher compression. It also lasts longer than pump gas, which means it can be stored for months without breaking down and making the fuel system dirty.

Also, avgas in particular has lead in it, which can cause more frequent plug fouling. It’s also not AMA-legal for competitive racing since they banned “leaded fuels”.

50/50 race gas & regular fuel - is mixing a BAD idea?

No, as long as you properly plan and use the mixed fuel - I’ve done it in one of my race bikes. If your dirt bike needs more than 91 octane but less than 100 octane, you can mix 91 premium and 110 race gas at a 50/50 equal mixture, this will give you a calculated 100.5 octane fuel mixture.

When is it bad to use mixed race and regular fuel?

One huge mistake that I made was using mixed race and pump gas that had been sitting for over a month. While race gas can last much longer, once it’s mixed, the fuel will break down faster.

What happened? It burned down the top end on my KX125 2-stroke and I had to get the cylinder replated because it was scored (scratches in the cylinder wall).

Can you run race gas in a stock motor?

Yes, but it’s probably not going to help because stock dirt bike engines don’t need higher-octane fuel. You only need race gas if you have higher compression or the fuel has power-increasing additives and you get your fuel system tuned specifically for that fuel.

Race gas in 2 stroke dirt bike - is it needed?

Most 2-stroke dirt bikes are made to be run on 91 premium pump gas or lower grades of fuel. The only way you'll need to use race gas in a 2 stroke is it the top-end is modified for more compression.

Why do people run race gas in stock dirt bikes?

Mainly because they think it’s cool or they believe a myth that race gas is always best but they’re throwing money away.
It’s sad, but true - if you’re running race gas in a stock dirt bike without proper tuning or changing anything else, then you’re just spending more money for a different exhaust smell and the same or potentially worse engine performance.

Pump gas - which is best?

In my experience, the best pump gas to use is one that’s rated for your engine and will last the longest before breaking down and causing fuel system issues.

Here are the most popular pump fuels in my area and how I rank them:

• 87 Regular: best cheap gas if you’re going to use it all within 1 month
• 91 Premium: best cheap 91-octane pump gas if you have a high-performance engine
• 91 Non-Oxy: longest lasting 91 premium pump gas

Will race fuel clean a carburetor?

No fuel, pump gas or race gas, will clean a carburetor unless it has cleaning additives in it. Even then, if a dirt bike has been sitting for over 1 year, it will likely need a full & proper carb clean to get it started and running well again.

Does racing fuel clean your engine?

Just like most fuels won’t clean the carb or EFI system, they won’t clean your internal engine parts unless they have a proven additive specifically designed for it.

What makes an engine or carb get dirty?

• Sitting in storage - gas breaks down and clogs up the fuel tank/lines/carb
• Sitting outside or high humidity climate - fuel attracts water over time, which causes the fuel to "gum up" and clog the fuel system
• Improper tuning (i.e. carb is jetted too rich)
• Using fuel with ethanol - ethanol attracts water and breaks down quicker if you let it sit for more than a few weeks

2 cheap ways to clean your dirt bike carb & engine - at the same time!

Rather than using an expensive fuel with special cleaning additives, you’re better off using proper gas (and oil if it’s a 2-stroke engine) with a proper air-fuel mixture to clean your engine of excessive carbon (unburnt fuel that builds up on the top-end parts).

Then, you need to properly warm up the engine and proceed to ride it hard. What does that look like? Accelerate with the throttle wide open and shift through all of the gears (Do this in a flat and open area).

This will suck the most fuel through the carb, get the engine hotter to burn out more unburnt carbon, as well as clean out the exhaust of unburnt fuel because the exhaust gases are hotter.

The problem with race bikes if you’re a beginner/novice

A common problem is riding at low to midrange RPM the whole time and not getting the engine hot enough. If you never rev the engine above 7000 RPM, you’re going to have more unburnt fuel stick to the internal engine parts and exhaust, causing it to clog up and lose performance over time.

What is a substitute for race gas?

If you just need a higher octane fuel, using 100LL avgas or an octane booster (Amazon) is the most effective way to prevent detonation in high-compression engines.

Beware: many so-called octane boosters claim to increase the octane but are deceptive or don’t work as well as claimed.

Scammy "Octane Boosters"...

For example, you might see an octane booster that claims “8-point increase in octane!”, but it means 0.8 points - not 8.0 numbers!

However, you can get a VP Racing unleaded octane booster (Amazon) that increases up to 7 full numbers (70 points) and can be used on up to 10 gallons of fuel.

Air-cooled vs liquid-cooled engines - why they have different gas requirements

Air-cooled 4-stroke engines, such as the Yamaha TTR230, are made to use 87 regular pump gas because they are lower-performance and it would be a limited buying factor. Think about it - you’re probably going to choose a trail bike if you’re out in the middle of nowhere doing work on the ranch and the only gas you can buy is very low quality.

A YZ250 MX bike engine is made for racing, which is why Yamaha tunes the engine for 91 premium gas because it can take advantage of that power and you’re more willing to buy it for racing purposes because you’re an experienced rider.

Race gas vs octane booster - how to know which you need

You should buy race gas if you:

• Need higher octane for a high-compression engine
• Will get the fuel system properly tuned for the race gas
• Need the best performance and throttle response
• Want the most consistent and longer lasting fuel over pump gas
• Don’t mind spending a lot more money on gas for your dirt bike(s)

You should buy an octane booster if you:

• Need higher octane for a high-compression engine
• Will be using the fuel within 1 month
• Want the cheapest “race fuel” to prevent detonation

Get the beginners "quick-start" guide

If you're new to dirt biking, I highly recommend grabbing my Beginners Quick-Start guide today for FREE - it will show you the #1 BIGGEST mistake beginner trail riders make as well as how to choose what dirt bike is best for you.

Either way, you’re in the right place if you want to know what kind of bike the KTM 350 is, why it may or may not be right for you, and what to expect when buying and riding one.

What is the KTM 350?

It's a 350cc liquid-cooled 4 stroke Enduro bike, which is basically a high-performance trail bike. The engine is based on the motocross race bike, but there are a few different models for the KTM 350 that are tuned slightly differently. 

Who's it for?

Depending on which model you get, which I'll cover the differences in a minute, the KTM 350 is great if you're an adult that's at least 5’8” tall and want a 4 stroke dirt bike with aggressive characteristics for racing, trail riding, or dual sport riding. 

Is it good for beginners?

If you’re riding on the road or easy and flat gravel trails, you might be able to handle one, but for the most part, I do not recommend buying a KTM 350 if you’re a beginner or just getting back into dirt bikes after 20+ years for a couple of reasons.

The 350cc 4-stroke engine has a lot of power, so if you start riding in the woods or on tight and technical trails, it’s very easy to grab too much throttle and have the bike jump out from under you - I hear about this happening way more often than I’d like.

If you’re a complete beginner or want a trail bike that will help build your confidence faster, then I highly recommend starting on a dirt bike that’s made for beginners - they’re cheaper, easier to ride, and easier to maintain.

350 EXC-F vs SXF vs XCF vs XW-F

• EXC-F: Street legal dual sport with power tuned down and softer suspension - full lights and plate for road and dirt riding
• SX-F: Motocross bike with the lightest and most aggressive power and suspension package
• XC-F: Cross-country race bike with close ratio transmission and stiffer off-road suspension
• XW-F (replaced XCF-W): Enduro bike with wider ratio transmission and slightly softer suspension with headlight/tail light

KTM 350 vs Husqvarna 350 vs Gas Gas 350 - is there a difference?

Since KTM bought Husqvarna and Gas Gas within the last several years, many of the dirt bikes between these two companies are very similar, and their 350cc dirt bikes are no different.

Other than the different colors of plastics, there’s very little difference between each brand’s 350 - Suspension components, airbox design, and other minor parts to slightly affect the price (Gas Gas is typically the lowest MSRP out of the 3 sister brands.

Engine characteristics

KTM first came out with the 350cc size dirt bike in 2011 to bridge the gap between a 250F that’s slightly underpowered for bigger or more experienced riders and the 450F that’s too exhausting to handle if you’re a weekend warrior. It’s a liquid-cooled, 4-valve, liquid-cooled engine that has decent torque at low RPM, but still likes to be revved high like a 250.

What to expect when riding the 350

The 350 EXC-F is the smoothest and tamest engine out of the 350 models, but even it has some “snap” to the throttle response, making it harder to control and more exhausting if you don’t have proper riding technique and good throttle control.

With that said, once you get into the midrange RPM, it really starts to pick up acceleration and pulls hard almost to the rev limiter around 12,000 RPM, which means it has a broad power curve, but you have to get above 4,000 RPM to get into the meat of the power - lower than that and you’ll feel it “chugging” and begging to downshift so that you don’t flame out/stall.

Horsepower

The KTM 350 SXF and XCF are very similar when it comes to the engine package - they both make about 50 rear wheel horsepower at just under 9000 RPM, according to Dirt Rider’s dyno, while the EXC-F model makes about 35 HP - yes it’s about 15 HP less than the other 350 models.

Why is the 350 EXC-F so underpowered compared to the SX-F & XC-F models?

Even though the engine platform is essentially the same as the MX and enduro race bike engines, the EXC-F is a dual sport motorcycle, which means that it’s street legal, which also means there are much stricter requirements to be legal.

This forces KTM to “choke up” the intake, engine, and exhaust to meet EPA and/or other regulations to make it legal to sell in every state or country.

Can the EXC-F be “uncorked” to be like the SXF and XCF?

While it’s much easier to start with a race bike if you want all that power, maybe you want the street legal benefit of the EXCF - then yes, you can modify or upgrade certain parts to bring that 35 horsepower up close to 50 HP.

The main things you need to uncork your KTM EXC-F 350 are:

• Tuning or replacing the ECU/ignition - Athena Get (Amazon)
• Better flowing exhaust (Amazon)
• Euro air boot
• Smog block off kit

Why HP doesn’t mean much

If you’re a trail rider like me, you’re not going to use half of the horsepower 90% of the time because you’re only ¼ to ½ throttle and in the midrange of the RPM, which means that most of us could get away with a 20 HP trail bike.

Unless you have the experience and skill to keep the RPM in the 7000-10000 RPM range, the low-end and midrange torque numbers are much more important because that’s where most of us spend the majority of our time while trail riding on single-track trails.

If you’re racing motocross or high-speed off-road courses, such as desert/hare and hound, then the peak horsepower is necessary.

Top speed

Much like peak HP numbers don’t matter, dirt bike top speed doesn’t mean much unless you’re drag racing or holding it wide open in the desert. With that said, depending on which KTM 350 model you choose, the max speed is about 70 mph on the SXF (MX bike) model and about 90 mph on the EXC-F (dual sport) model.

A simple gearing swap will change the top speed and acceleration of your dirt bike. For example, going to a smaller rear sprocket (Amazon) will increase the top speed while losing a little bit of acceleration - a good compromise for dual sport riding if you want to cruise at a lower RPM and don’t need a really low 1st gear.

Transmission differences

There are 4 KTM 350 dirt bike models with slightly different transmissions. The wide-ratio transmissions have gears that are spaced further apart, making each gear more usable (less shifting), while the close-ratio transmission has gears that are closer together.

This makes it easier to keep the power in the meat of the RPM range and have better acceleration as you’re upshifting, but it also requires more frequent shifting.

These are the KTM 350 transmission differences:

• EXC-F: 6-speed, wide-ratio - 1st gear is fairly low for some moderate trail riding, while 6th gear is taller than average for higher cruising speeds on the road.
• SX-F: 5-speed close ratio - 1st gear is fairly tall with all 5 gears being closer together so it’s easier to stay in the right RPM for racing motocross
• XC-F: 6-speed close ratio  - 1st gear is fairly tall with all 6 gears being closer together so it’s easier to stay in the right RPM for racing off-road
• XW-F (replaced XCF-W): 6-speed, wide-ratio - 1st gear is fairly low for some moderate trail riding, while 6th gear is taller than average for higher cruising speeds on dirt roads

Reliability

Being a high-performance engine that’s made for racing, the KTM 350 will require noticeably more maintenance than a beginner trail bike in the long run, but that doesn’t mean it’s noy reliable. In fact, if you’re doing regular oil and filter changes and keeping the air filter clean, all KTM 350 models can be surprisingly reliable - depending on how you ride it.

How long will the engine last before needing a rebuild?

If you’re an expert rider that rides at high RPM and is constantly hitting the rev limiter, you’re going to need the engine rebuilt sooner than later - no matter what dirt bike you choose. You can expect to need a rebuild in the 20-50 hours range with those conditions.

However, if you’re a casual trail rider or dual sport rider that is easy on the throttle and rides in the low to midrange RPM, you could easily get 200+ hours or 3000+ miles before anything needs to be done to the engine, assuming you’re doing proper maintenance.

Suspension

Once again, there’s a range of differences between each KTM 350 dirt bike model, but they’re all high-performance compared to a beginner trail bike. That’s not necessarily good, especially if you’re new to riding dirt bikes off-road.

Why? These “race bikes” are made to be ridden fast, so if you’re riding too slowly, the suspension will feel stiff and harsh, making it uncomfortable and fatiguing on your arms, wrists, and hands.

Front forks & rear shock

KTM has made small and large updates to each 350cc model over the years, so I’m just going to compare the main differences of what you can expect for any year 350 based on the type of dirt bike you pick.

Here are the practical suspension differences between each KTM model:

• EXC-F: The softest suspension out of the group - it’s made for dual sport riding, which is a wide range of pavement, gravel roads, and mild to moderate trail riding
• SX-F: Stiffest suspension that’s made for one thing - racing motocross with big jumps, whoops and rough terrain on MX tracks
• XC-F: Stiff for racing, but slightly softer than the SXF model because it’s made for off-road riding and can handle small jumps and whoops before bottoming out
• XW-F (replaced XCF-W): Noticeably softer than the XCF model - made for the more casual trail rider while still being stiff enough for experienced riders.

Suspension adjustability

All of these KTM 350’s are made for the average person that’s about 5’10”-6’0” and 160-180 lbs. You can adjust the compression and rebound damping to get a slightly stiffer or softer feeling, but if you’re much lighter or heavier then you will probably need different springs and/or suspension re-valve.

When should you consider a suspension re-valve?

With that said, I highly encourage you to ride the stock suspension settings before sending your forks and shock out for a $1500+ re-valve. If you don’t know how the stock suspension components perform and how you want them to perform differently, then the tuner is not going to know what “better” means when you tell them to “make it better”. 

This goes for any dirt bike - it can save you a lot of time and money if you just spend a little bit of time trying to understand your dirt bike. It’s also a fun challenge and makes it exciting when you can make a change on your dirt bike and notice a positive difference that makes you more comfortable while riding!

Size & Handling

All KTM 350 models have around the same seat height (37.6”), which is about as tall as it gets for a dirt bike and is a comfortable size if you’re 5’10”-6’2” depending on your inseam length. With that said, the seat height doesn’t matter as much once you’ve mastered the basic techniques for trail riding.

If you’re a beginner and have short legs like me or are under 5’10”, this full-size dirt bike will feel tall - as in it’s easy to tip over when you come to a stop if you don’t have good balance.

Once you start moving it’s not a problem and you shouldn’t be putting a foot down while riding because you don’t have full control over the bike, but it does give you more confidence if you’re just starting if you can put a foot down without worrying about falling over half the time.

Weight specs between the models

KTM has always been at or near the top when it comes to having the lightest dirt bike in its class. However, I believe they can be a little deceptive or just not even list the specs when it comes to the actual weight of their dirt bike models. 

For example, all four of the KTM 350 dirt bikes range from 225-232 lbs according to the specs I could find on their website. That’s very light for a 350cc dirt bike, but there are two problems I see…

Are the weights accurate?

The listed weights are “without fuel”. That means you can add 12-15 lbs to each bike for the actual “wet weight” - a realistic number for riding because you don’t start riding with an empty fuel tank.

The other potential problem is that the 350 EXC F dual sport model is the 2nd lightest out of the 4. It SHOULD be the heaviest because it has the most equipment to make it street legal (lights, blinkers, horn, mirror, exhaust, etc…)

Model year history & changes

• 2011: First year of the 350 SXF (Motocross bike)
• 2014: Reliability updates to the engine
• 2017: Major update to all bikes (more power and less weight)
• 2020: Chassis updates to make it turn and handle better
• 2024: EXC-F model gets similar updates to previous year other 350 models to improve overall performance & handling

Price

MSRP ranges from $10,699 for the 350 SX-F to $12,149 for the EXC-F model, but then you also have to add dealer fees and taxes, which could be another $1-2k out the door.

If you don’t mind buying a used dirt bike, you can find them in the $4000-8000 range depending on the year, condition, and model. You’re local market supply & demand also play a role in the value of dirt bikes.

Is it street legal?

The only KTM 350 model that’s street-legal from the factory is the 350 EXC-F if you register it for the road. The XF-W (XCF-W) model has a headlight and tail light, but it’s made for off-road use only and requires a few other parts to meet the street legal conversion checklist.

Is the 350 EXC-F good for riding on the road?

For a dual sport motorcycle, the 350 EXC-F is extremely light, which makes it a good off-road bike if you’re a more experienced rider who can handle 35+ horsepower. It can handle riding on the highway, but it’s not the most comfortable dual sport bike for long pavement rides for a few reasons.

Lightweight dual sport bikes get pushed around more, which is more tiring while cruising at 55+ mph. The engine is also fairly “buzzy” at higher speeds, which can get annoying and exhausting as well. There’s also no real wind protection, so you’re going to get a lot of wind (and bugs) in your face.

Any common issues?

There are occasionally some issues with the first model year of a new generation (when 90-100% of the bike is new/updated), but for the most part, all KTM 350 dirt bike models are good if they have been well maintained.

Specs & dimensions

These are the most accurate specs I could find for all four KTM 350 models:

Is the KTM 350 the right dirt bike for you?

Still can’t decide if the KTM 350 dirt bike is right for you or which model to choose?
Here are some practical pros & cons of these bikes:

Pros:

• Power to weight ratio is great - plenty of power and good handling
• All years have EFI and electric start
• EXC-F is a great dual sport bike if you want to do more challenging trail riding
• XW-F (XCF-W) is great if you’re a skilled rider who likes tight & technical trail riding
• XC-F model is great for expert racers or high-speed trail riding
• SX-F is great for motocross
• More power than 250 but is less tiring than a 450
• 4 strokes can last longer before needing a rebuild
• No mixing gas

Cons:

• More power than any beginner needs - easy to twist the throttle and lose control
• Expensive
• Slightly more maintenance compared to a lower-performance trail bike
• Parts can be more expensive than Japanese-brand dirt bikes

Six Days model - what is it?

Every year KTM releases a new & unique-looking “Six Days” model that doesn’t perform differently than the standard model but looks different. They model it after the country colors that is hosting that year's International Six Days Enduro race (ISDE) with different plastics, graphics, and some anodized parts on the bike.

350 EXC-F vs 350 XC-F

The main difference is that the EXC-F 350 is a dual sport bike that is street legal with full lights, softer suspension, and a milder engine tune, while the XC-F 350 is an off-road race bike with stiffer suspension and an aggressive and powerful engine tune.

What to look for when buying a used KTM 350

There are so many things to inspect on a used dirt bike, but there are a few specifics that people often forget to look for that end up with you buying an unreliable dirt bike. Check out this video below for the first things I look at to know if a used dirt bike is good or bad.

Then click here to learn the top 5 mistakes buyers make when buying a used bike.