Why Does My Dirt Bike Backfire?


If you have experienced a dirt bike backfire, you know of the irritating sound that comes with it, and you may have wondered if it can damage your engine.

Backfiring happens when there is a malfunction in your dirt bike’s emission system, where incorrect quantities of the air-fuel mixture lead to incomplete combustion. A backfire can happen on acceleration, de-acceleration, and start-up.

Once you experience a backfire, you can do a quick analysis of your bike using simple tools like wrenches and screwdrivers. Check the air filter, carburetors, and jets for any blockages.

If you cannot detect the source of the issue, it may be time to take the bike to a mechanic. Read on to know more about the issue and its remedies:

What is Backfiring in Your Dirt Bike?

A backfire manifests as a banging or popping sound from the exhaust or intake system of your dirt bike. The explosion is supposed to occur in the engine’s combustion chamber of your, and it, therefore, affects the functions of the motor.

The engine can backfire if there is too much air or fuel. The heat of your bike’s exhaust ignites the fuel and causes incomplete combustion. Some exhausts can even produce a partial flame with the potential to start a fire.

How to Tell if Your Engine is Running Rich or Lean?

An engine runs rich if there is more fuel in the combustion chamber than air. The explosion needed in the combustion chamber to propel the piston will not occur, and the excess fuel will drain into the exhaust. A banging sound can be heard as the bike backfires.

You can tell if the air/fuel mixture is too rich if there is a potent gasoline smell when the bike is idle or if the engine is running unevenly.

If your engine is running lean, there is more air in the combustion chamber, and your engine is starved of fuel. The fuel will pass into the exhaust and explode from the exhaust’s heat. A startling popping sound will then ensue.

You can adjust your air/fuel mixture at home while the engine is at running temperature. Using a screwdriver, adjust the two screws on the carburetor a quarter turn at a time to get the engine running smoothly.

Factors that Cause Your Dirt Bike to Backfire

Here are few factors that can cause your dirt bike to backfire:

Malfunctioning Spark Plugs

Your spark plug can cause a motorcycle to backfire if it does not spark after opening the exhaust valve. A misfired plug will quickly ignite the unburned fuel that is present in the exhaust system.

A bad spark plug can also have incorrect ignition timing with the compression, or it can be too worn out to perform its job.

Dirty or Bad Carburetor

The carburetor mixes fuel and air in the combustion chamber, although some bikes have a fuel injection for the same function.

If your motorcycle stays idle for too long, the old gas in the carburetor will accumulate a lot of impurities. Such debris will affect the working of your engine and cause a backfire.

A bad carburetor can also affect the performance of the engine. It will deliver a lean fuel/air mixture and cause overheating and backfiring.

Lack of Compression

Compression drives the piston movements in the combustion chamber. If your bike’s cylinder has improper compression, the spark plug will not ignite the air/fuel mixture.

A leaky exhaust valve can also cause a lack of compression.

Clogged Air Filter

Dirty air filters are common culprits when it comes to dirt bike backfires. If your air filter is clogged, your motor will not be able to get the adequate air it needs in the air/fuel mixture to power the bike properly.

It is easy to forget about the air filter until such issues arise, which is why routine maintenance is needed.

Dirty Jets

A carburetor has four components that need to be kept dirt-free. These parts are the Needle Jet, Jet Needle, Main Jet, and Pilot Jet, and they will affect the functioning of the carburetor if they accumulate a lot of debris.


The Octane levels in your fuel can also cause backfiring, and it is always advisable to use a high-grade high-octane fuel.

How to Prevent Dirt Bike Backfire?

You can safeguard your bike from backfires through:

Clean the Carburetor

If you check and determine that your carburetor is clogged, it is best to clean it thoroughly. Buy a carburetor cleaner and start by cleaning the carburetor exterior.

Remove the housing as well as the jets and spray them with the cleaner. Do not forget to clean the air duct leading to the carburetor.

Utilize Fuel Injector Cleaner

If you have a fuel-injected bike, you will need to get a high-grade cleaner. A quality cleaner will get rid of all the debris and dirt that can cause blockages.

Clean the Air Filter

The condition of the air filter affects how well your engine performs and lasts. The filters get clogged quickly if you often take your bike to muddy and off-road trails.

If you ride the motorcycle infrequently, you can get away with cleaning the air filter once every six months or after 3,000 miles. Air filters also tend to get worn out relatively quickly, but the good news is that they are inexpensive.

Use High-Grade Fuel

There are different qualities of fuel available, and some will be kinder to your dirt bike than others. The manufacturer will typically recommend the kinds of fuel to use based on the make of your model.

Ensure your bike runs on high-quality fuel as it will minimize the additive buildup in gasoline. You can expect a cleaner engine as compared to what you would get if you used low-quality fuel.

Is a Backfire Bad for My Bike?

A single backfire will spare your engine, but you should take the issue seriously if it keeps happening. You should also determine the level of sound that the exhaust produces.

A mild cough may not indicate serious consequences, but the same cannot be said for a loud bang.

Backfiring also causes the loss of power, while running a rich or lean mixture will only fry your engine. In the long-run, backfiring will damage the exhaust, and you will spend a lot on repairs and replacements.


As demonstrated above, backfiring often results from having a dirty bike. Clogged air filters, carburetors, or jets are common culprits in addition to low-grade fuel.

It will be time to consult a mechanic in case of continuous backfiring to avoid extensive damage to your engine.

Josh Berry - MotoShark Editor
Josh Berry

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