What Causes White Smoke From a Dirt Bike

We’ve all gotten a bit if a fright the first time we saw white smoke coming from our dirt bikes, wondering why and if it is something serious that will cost a lot to fix. Luckily, you’re in the right place and we’ll take a look at what causes white, and other colors, smoke to come from your dirt bike, when to worry about it and what to do to fix it.

It is normal for a dirt bike to expel white smoke while the engine is cold, but if the white smoke continues while the engine is warm, it is most likely due to excess water in the engine and usually nothing to worry about. If a dirt bike, however, expels black, grey, or blue smoke, it is an indication of a more serious issue that needs to be addressed.

So let’s dive in and examine this in more detail.

White smoke coming from your exhaust is usually nothing to worry about. If you start your dirt bike and the weather is cold, your dirt bike will usually create white smoke until the engine warms up.

If your dirt bike is still smoking even after the engine has warmed up, it could be due to a build-up of water somewhere in your engine. A build-up of water isn’t a serious issue, but it is best to solve the problem sooner rather than later.

If your dirt bike is expelling black or blue smoke, then there might be a minor problem with your bike. We will discuss the different types of smoke, what they mean, and solutions to the problem. First, let us talk about white smoke.

White smoke

As we mentioned above, white smoke usually isn’t something to be worried about unless the exhaust is expelling white smoke even when the engine is warmed up. After starting your dirt bike, give it a minute or two, and it should stop smoking. If there is excess water in the engine, your bike might smoke for longer.

The easiest way to solve the issue of having excess water in your dirt bike engine is to lift the front tire in a wheelie position, after that, disconnect one of your spark plugs and flip your dirt bike over. Let the dirt bike rest on its handlebars for a minute or two. That should allow the excess water to drain out of the engine. Remember to be careful and only do this on a flat dry surface.

Another cause could be excess oil in the reservoir. If this is the problem, then all you have to do is drain some of the excess oil from the reservoir, start your dirt bike, let it warm up, and see if it continues to smoke.

If you have drained the excess oil from the reservoir and your dirt bike continues to smoke, or if you have checked the oil reservoir and it was not over full, it is time to check the cylinder heads, pistons, and seals. You want to thoroughly inspect these components to check for cracks, gunk build-up, and wear and tear. Any of these issues can be caused by general wear, overheating of the engine, and/or reckless driving.

That is pretty much it regarding white smoke. To complete the steps we have highlighted above, it would take you approximately three hours. You can do it at home or take the bike to your mechanic, if any parts need replacing, they are generally inexpensive.

Black smoke

Now that we have covered white smoke, I think it is essential to talk about black smoke and what it means.

If your dirt bike is expelling black smoke from the exhaust, again, this is not a major issue, but you want to sort it out as soon as you can to avoid further damage to your dirt bike.  Black smoke often has something to do with your fuel mixture being too rich, which affects the combustion efficiency within your engine.

If you are wondering how the combustion efficiency can cause smoke, it is because any fuel that is not burnt will be sent through the exhaust system and will then be burnt downstream in the combustion chamber.

Another common cause behind this problem can be due to a number of components such as a  blocked fuel return pipe, a faulty air flow sensor, a faulty air filter, a fuel pressure regulator that is jammed, a leaking fuel injector and a dirty air filter. Any one of these issues can be the reason why your dirt bike is creating black smoke.

To solve this problem, it might take you a couple of hours, depending on how long it takes you to identify the problem.

Blue smoke

If your dirt bike is creating blue smoke, it could be due to a few causes, but the most common cause is cross-contamination between your fuel mixture and oil. The contaminants get into cylinders due to damaged, worn or broken seals.

Damaged piston rings can also be one of the reasons why your cylinders are experiencing a cross-contamination problem and causing your dirt bike to create blue smoke. When there is a damaged seal or piston ring, the oil will get sucked into the combustion chamber along with the fuel mixture.

This is actually a common problem, especially when buying second-hand dirt bikes as most people don’t check the health of the bikes seals, rings, and valves.

Fixing this issue will take you around for hours. You will need to have at least a little bit of experience as you will be dealing with your pistons and carburetor.

If you are not sure how to get to the carburetor on your dirt bike, we do have articles explaining the process.

Grey smoke

Your dirt bike might be expelling grey smoke from the exhaust. The causes behind this are similar to the causes behind blue smoke. If you have a two-stroke bike, grey smoke is perfectly normal, the only time it becomes a problem is if it is on a four-stroke. The most common cause is oil pushing past your piston rings and getting into the combustion chamber, this causes cross-contamination with your fuel mixture.

The solution is the same as the blue smoke solution.


In conclusion, if your dirt bike is creating white smoke, it is usually nothing to worry about, if the white smoke still continues while the engine is warm, it means you have excess water in the engine. We have explained how you should go about draining the excess water.

We have also discussed the different types of smoke and what they mean. Remember that if you are ever unsure of something, feel free to come back to this article. Also, don’t be afraid to ask for help from someone if you ever need to.

Stay safe and happy dirt biking!.

Louis Pretorius

As an amateur off-road enthusiast, I have always been drawn to outdoor adventure. I have decided to share all of my learning experiences with you as I dig a little deeper into my new-found passion and wonderful world of off-roading. My mission is to create the Ultimate Off-roading space on the internet in the process. Stay safe and happy Off-Roading!

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