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Is A Glowing Red Head Pipe Okay?

Wondering why you have a dirt bike exhaust glowing red and if it’s okay? Whether you just got your bike or you’ve had it for a while and it started getting red hot, you’re in the right place!

In this article, I’ll explain what it means when the exhaust is glowing red, whether it’s okay or not, the most common causes, and how to fix it.

Is a glowing red dirt bike exhaust okay?

No, but it doesn’t necessarily mean anything bad has happened…yet.
Is it “normal?” Yes.
Is there a way to fix it? Yes, there’s more than one possible solution, although there is one that stands out the most.

If the head-pipe is red, that means the engine is getting too hot and needs more cooling. You may not need any parts to fix this though; let me explain…

dirt bike head pipe glowing red hot
Head Pipe Glowing Red Hot

How long does it take exhaust to cool down?

If your head pipe is glowing red, you can shut the engine off and let it cool down so that it doesn’t do any (more) damage. This can take anywhere from 5-30 seconds to cool down and stop glowing, but it may take 5-15 minutes for the engine to cool down enough to safely ride again if it actually overheated.

Dirt bikes that most commonly have a glowing red pipe problem

Basically any 4 stroke dirt bike can have this issue, but there’s certain dirt bike models that have a frequent problem with the exhaust pipe glowing red.

  • Suzuki RMZ250
  • Honda CRF450R
  • Yamaha YZ250F
  • Kawasaki KLX230R

What Causes A Dirt Bike Head Pipe To Glow Red?

There are a number of reasons why it’s glowing red, and they range from simple to somewhat complex.

How long are you letting it idle?

There are two ways a 4-stroke dirt bike “cools”. Both of them require riding the bike, so don’t think you can stop and wait to let it cool down.

In fact, you want to do just the opposite. First of all, riding the bike gives it air-flow through the radiators (If it’s liquid-cooled), naturally.

So if you’re standing still, the cooling system isn’t going to do a whole lot. This is the most common issue for beginning riders and trail riders that do tight single track. The more you stay moving the better.

Head pipe getting red hot from sitting idling

Gas Cools It

The next possible solution is similar to the first, but in a different way. You now know that riding at higher speeds will reduce the chances of overheating because radiators need air-flow.

Gas is the other cooling part. The more gas going through the cylinder head and combustion chamber, the more it will keep it cool, to an extent.

Like before, if you’re sitting with the bike idling, it’s not getting enough gas to burn and keep cool, even if your jetting may be correct (although, lean jetting can also cause overheating problems).

Do air-cooled dirt bikes overheat?

A lower-performance air-cooled trail bike should not have a glowing head pipe from idling. If that is the case, then the jetting is too lean, or the EFI is too lean and needs to be richer.

This can be done with a bigger pilot jet for a carburetor, or richening the EFI system with a fuel programmer.

And if you want to improve your trail riding skills so that you stay in control and prevent bad crashes, I have a super quick and practical training guide that shows you the basic techniques you need here.

Jetting too hot

If your dirt bike has a carburetor, then some proper jet tuning can make a huge difference in how your bike runs.

If everything is working well, but the jetting is too rich or too lean, then your dirt bike may be: hard to start, have poor throttle response, overheat faster, be less reliable, and more.

Jetting that is too lean will cause the engine to run hot because it’s not getting enough fuel to properly cool it.

Exhaust change without EFI tuning?

Does your 4 stroke dirt bike have fuel injection? Making an exhaust, or even a modification to the engine or intake will make it run differently.

The EFI on most dirt bikes is an open-loop system. This means it only takes account of the air temp/humidity.

What’s the result?

The system doesn’t know if it’s running the stock exhaust or no exhaust at all, which will greatly affect the air-fuel mixture. It only adjusts the fuel mixture when the climate you’re riding in changes.

So, if your 4 stroke is running hot after an exhaust system change (even just a slip-on), there’s a good chance that you need to get the EFI tuned.

This might be a new ECU and controller, just the controller, or maybe your specific bike has an app available to tune it with WI-FI.

Valves wear out quicker with heat

It’s not necessarily the entire engine that overheats from a lack of gas. It’s the valves that start to heat up and eventually burn out.

If you’ve been around 4-stroke motocross bikes at all, you have probably heard the term “Burnt a valve.”

Well, this is one of the main reasons why it happens. The valves just get too hot too many times, causing them to burn up the edge and lose all compression. It’s better than dropping a valve, but still can be a costly repair.

How to make your valves last longer

Properly warming up your dirt bike is part of it, which is why I never let my four-strokes idle for very long when I first start them up.

How do I know this, you ask? Well, I know of many people that have burnt valves more often than usual, and it wasn’t coincidence. No, it was because they putt around on their bikes.

Not only does riding your bike harder and faster give it more air to cool it down, but it also gives it more gas to keep the valves cool, increasing longevity.

You will also have more fun riding faster because you’re passing your buddies that are cruising along.

All in all, a 4 stroke motocross bike is made for one thing; to be raced, and raced to its potential. You don’t have to out-ride yourself, and I suggest you don’t.

But, the more speed you can get, the better off your dirt bike will be. Quite the contrast compared to most other things, huh?

Dirt bike running hot after sitting in storage for months?

Did you just pull your bike out and now it’s running hot with the head pipe glowing red. You haven’t changed anything since you rode a few months (or possibly a few weeks) ago, so what’s causing it?

If it’s carbureted, then it’s most likely due to it being dirty. The jets and passages are so small that it doesn’t take much of a spec or gas breaking down to gum up and block it.

This changes the air-fuel mixture because less gas is getting through the partially blocked passage. Less gas = lean and running hotter.

A quick draining of the float bowl may get sediment that settled out, but a carb that’s been sitting for a while may need a full and proper cleaning.

Dirt bike exhaust glowing red summary

The most common causes of a dirt bike head pipe glowing red are:

  • Idling too long
  • Dirty carb
  • Engine is not getting properly cooled
  • Improper jetting
  • EFI not tuned correctly

Free ways to prevent overheating

Want to learn how to keep your dirt bike running cool? These tips are Free to do and will help prevent a catastrophic failure that could leave you stranded in the middle of nowhere. Click here to learn how.

Ben

Sunday 26th of June 2022

Hi do you have a 05 yz450f header pipe,and do you ship to nz

viktor

Tuesday 29th of June 2021

100% helpfull. Thanks

Kelley Fager

Wednesday 30th of June 2021

Glad it helped. Thanks for reading, Viktor.

Jeff

Saturday 21st of November 2020

I just bought a 2021 Honda CRF 450RL. I started it up at the dealership thinking I’d let it warm up a bit before loading it in the trailer. The dealer reached over and turned it off saying that I don’t want to let it idle because the exhaust will get red hot. Got it home and putted around the block a couple times in the cold. When I pulled into the garage I left it running for a minute to do a walk around and noticed the header begin glowing read. Brought the TPMS up just a couple hundred and watched the red glow extend down the pipe almost to the seat in just a few seconds. This sure doesn’t seem right on a brand new $10000 bike.

Jordan

Sunday 22nd of May 2022

@Kelley Fager, I have the same bike. Get a vortex ECU, yoshi header, and yoshi slip on. Bike will be so much more responsive and smooth but also fix your problem. I've let it ideal every bit of 5 minutes and have never gotten a red pipe. I guess your elevation and humidity could play a part too though. I'm in Michigan. Best of luck

Kelley Fager

Saturday 21st of November 2020

The CRF450L is the street legal version, so the fuel injection system is probably mapped to run lean to meet EPA emission regulations. Lean = hotter running engine, so I'm not surprised that your brand new bike is running hot when idling. The other problem is simply that a liquid cooled bike needs air flowing past the radiators to cool it down. Even if the EFI is rich enough it will eventually get hot if you just let it sit and idle too long. This results in the glowing head pipe you saw. You can either get it re-mapped, or just ride it and don't let it idle too long.

Julie

Saturday 3rd of October 2020

Very insightful, thank you! I have an 06 yz450f. We just rebuilt the top end and during first fire the header started glowing within 10-15 seconds. The carb was leaking fuel so it was definitely running lean. We are obviously going to pull the carb and button it up but considering how fast the pipe started glowing, do you think there could be another factor aside from just the lack of fuel?

Kelley Fager

Saturday 3rd of October 2020

Hard to say. Lacking fuel would definitely cause it to run hot that quickly. I would solve that and then see what happens. One thing at a time so you know what causes or fixes an issue.

Caden

Thursday 1st of October 2020

I have a 2014 crf150r and the header got cherry red.I read this and should I just let it idle for a little and then go ride and it shouldn’t be glowing what do I do?

Kelley Fager

Thursday 1st of October 2020

Hey Caden, any 4 stroke race bike head pipe will start glowing red if you let it idle too long. It needs airflow to cool the engine down. The jetting could also be on the lean side. Has it always done this?