Exactly How a Dirt Bike Can Start a Fire


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Dirt bikes can get hot when they’ve been running for a long time or sitting under the sun. If you’ve ever touched a dirt bike’s engine after it’s been running for a while, you know this firsthand. But just how hot do they get and could they start a fire?

Dirt bikes can potentially start fires, especially in dry grassy fields. It’s important not to go dirt biking in such places when there’s a burn ban, as it can easily end in disaster. That being said, it’s fairly unusual for dirt bikes that aren’t broken to start fires outside of this situation.

So there’s actually quite a bit to this little safety fact. Different bikes will burn in different ways, and the risks of a fire are vastly increased if the bike has any kind of fuel leakage. Let’s get into the nitty-gritty of what makes a dirt bike burn.

How Dirt Bikes Start Fires

In the United States, we have a law that requires dirt bikes and other motor vehicles to have what’s known as a spark arrestor. Essentially, the spark arrestor prevents hot residue from escaping out of the vehicle’s engine and starting fires.

There is some debate in the dirt biking community as to whether dirt bikes can even produce that kind of matter, but I’ve definitely heard stories that make it seem like a possibility.

The real culprit when it comes to a dirt bike that starts a fire is the engine. The hottest part of a dirt bike can get up to 1,200 degrees Fahrenheit. That’s nearly hot enough to melt steel! Thankfully that part (called the head pipe for you mechanics out there) usually isn’t exposed, but the rest of the engine can still get pretty hot. In fact, the engine can get up to 600 degrees, which is definitely enough to start a fire.

The ignition point of dry grass is 572 Fahrenheit, which mathematically speaking, is less than 600 degrees. That means that if dry grass comes into contact with a hot engine, there’s a really good chance that it will just burst into flames.

This usually happens when a biker falls off their bike or otherwise fails to stay upright. If the engine remains in contact with the grass for too long without anything being done, it can easily turn into a brush fire that destroys the bike and potentially a lot more.

Grass fire started by dirt bikes.

This problem is compounded by the likelihood that the increased heat combined with the impact of the crash has a good chance of causing the gas tank to leak, making the fire risk significantly more severe. If this happens, the bike will pretty much always be destroyed.

The fire will also be incredibly difficult to put out if this happens since the addition of gasoline means that water will now only make it spread worse. If you’re worried about this happening, you should always bring a fire extinguisher with you when you go dirt biking.

How Often Do Dirt Bikes Cause Fires?

The fact is that even though dirt bikes can absolutely cause fires, this doesn’t happen very often. This may be a factor of dirt biking being less common than irresponsible smokers or poorly timed campfires, but statistically speaking they don’t cause fires nearly as often as other things might.

There isn’t really any currently existent database of fires caused by dirtbikes, which means that keeping track of them is incredibly difficult.

However, there is a sufficient amount of anecdotal evidence for me to believe that it is certainly possible, especially if you park your recently ridden dirt bike near or in dry vegetation. Because the engine gets so hot and has a solid chance of leaking gas, the fires can start in an instant and will be difficult to put out without assistance from professionals.

NEW TO DIRT BIKES? Learn how to go about riding a dirt bike for the very first time including what type of terrain to start on to promote a safe (and fire-free) riding experience! Check out our article all about how to ride a dirt bike for the very first time for more on this.

An Example of a Dirt Bike Caused Fire

This is the most famous example I was able to find. Watch how quickly the fire starts underneath the bike and how a significant amount of grass was burned.

Once the fire gets this big, it doesn’t need a heat source anymore. This means that even if you can get the bike out of the area of the fire, it will likely continue until it reaches something it can’t burn. Then, even when it looked like the fire had been totally extinguished, it started back up again even bigger.

Fires like this can get really bad, really fast.

COMMON CONCERN

Does all this talk about starting fires make you wonder exactly how safe the sport of dirt biking is overall? See some very interesting statistics about the safety of dirt biking as a family sport that really puts things into perspective in the article Dirt Biking Dangers: Is It a Safe Family Sport?.

Preventing Dirt Bike Fires

These fires can be dangerous for more reasons than just one. They may start only threatening you and your bike, but they can quickly spread so that homes, towns, and other kinds of personal property can quickly end up in the path of the flames.

Perhaps an equally scary outcome: If dirt bike fires have a big enough impact on the region where they take place, bikers could end up facing restrictive regulations or even bannings. However, there isn’t really any reason that these fires should ever get very bad.

Of course, making sure that you always have your spark arrestor properly installed is a great way to start, but there are other things that you can do to mitigate the risk of starting a fire.

Grass fire spreading fast.

Whenever you park your bike, make sure that there are no dry plants nearby. Gravel, dirt, or asphalt parking lots are all good places to leave your bike, but if none of those are available make sure that at least the bike isn’t parked over grass or vegetation that could catch fire.

While if you’re only going to stop for a few seconds it might be fine to park over grass, it certainly could cause problems if you leave it for any amount of time.

You can also carry a small fire extinguisher with you whenever you take your dirt bike off-road. While there isn’t much that it can do if the bike itself is on fire and the fuel case has been compromised, for a situation like the one in the video above a quick enough application of a fire extinguisher might be able to nip the flame in the bud.

More Helpful Information

  • Our Recommended Dirt Bike Gear – If you are new to the sport of dirt biking or even just considering getting involved, take a look at our most recommended (and trusted) dirt bike gear that every rider should have. This cuts through all the hype and gives you a list of what actual experienced dirt bikers are buying and using in the field.
  • 21 Best Dirt Bike Accessories That Every Owner Should Have – There are some things you should always carry with you on a dirt bike not just for a safe riding experience, but to make sure you enjoy your time out as much as possible. The pros know these things, and you should to. Take a look at this article for more!

John Hayes

A street biker turned dirt bike rider, I've been riding motorcycles since I was 12-years-old and have a passion for the technical aspects of dirt bike riding.

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