You have bought a great dirt bike model from your dream manufacturer. But, you are experiencing the backfire issue of late and you don’t only feel uncomfortable, but also scared when you hear that banging sound from the exhaust.
Does it seem to be your story?
Well, if you are one of the motorcyclists who have no idea about what makes a dirt bike backfire, you have come to the right page.
In this article, we are going to share with you some of the common causes of dirt bike backfire and show you some of the effective ways on how you can prevent your motorcycle from backfiring.
Just make sure that you read this complete post to understand everything you need to know about dirt bike backfires. Let’s go ahead now.
What Does Backfire in the Dirt Bike Mean?
A backfire is a malfunction of the emission system often reported by dirt bikers or motorcyclists. The main reason for the dirt bike backfires lies in the incorrect ratio of air and fuel.
When your bike fails to maintain the correct fuel and air ratio, which is required not to be too rich or too lean, the backfire occurs.
To be frank, it happens because the combustion remains incomplete.
So, when does a backfire usually occur? It can occur when you start the bike, accelerate, or even when you decelerate.
A backfiring in a dirt bike is almost always accompanied by an irritating popping or banging sound.
A dirt bike backfire can be potentially dangerous especially when it comes to flames and sparks. The flames that erupt from the exhaust pipe can even initiate a fire.
Why Does Dirt Bike Backfire?
The main cause of the backfire in the dirt bike lies in the imbalance of air and the fuel. When your engine runs too rich or too lean of fuel, your dirt bike starts to backfire with a loud sound. The malfunction in the emission system is the direct outcome of an engine running too rich or too lean.
So, what do we mean by ‘engine running too rich’ or ‘engine running too lean?’
Well, when the engine is swamped with too much fuel compared to the air, the condition is assumed as running rich. When your engine runs rich, it is almost starved of air and overflowed by fuel.
On the other hand, when your engine is starved of fuel and swamped with air, this condition is assumed as running lean. In this scenario, the dirt bike engine does not get enough fuel and the air pressure fills the gap.
However, there are a variety of reasons why the engine runs too rich or too lean. Let’s discuss some of the most common causes that contribute to the dirt bike backfire.
Common Causes of Dirt Bike Backfire
There are many causes why you might experience the backfire issue in your dirt bike. Here are some of the most common cause that creates a backfire:
Dirty or Faulty Carburetor
In most of the dirt bikes, the carburetor plays the role of mixing the air and fuel to the right proportion in the combustion chamber.
If you are not using your dirt bike for a long time, the old gas can create debris and impurities. That type of debris affects the engine negatively and causes a backfire.
Make sure that the mixture and idle screws in the old carb are properly adjusted.
A bad carb is also responsible for engine running too lean issues. The ultimate outcomes are backfiring, failure in accelerating, and overheating.
A dirt bike can be dirty if you do not check and clean it manually from time to time. If a carb is faulty, the fuel cannot pass through it smoothly.
The piston movements in the combustion chamber take place with the help of compression. In case your bike can not maintain an adequate amount of compression, the spark plug will likely fail to ignite the air and the fuel.
Low compression can occur due to a variety of factors. A leaky exhaust valve is one of them.
Clogged Air Filter
Dirt can easily block the air filters and thus cause a backfire. Once your air filter is blocked with debris, it cannot supply the required amount of air in the fuel/air mixture part to power the bike properly.
Do not forget about the air filter to clean routinely so that you do not have to face the bad experience of backfiring.
Bad Spark Plugs
A bad spark plug can be responsible for the dirt bike backfire.
How do you know that a spark plug is not working properly as it should?
You have to check it manually. Do not worry, checking the spark plug is one of the easiest tasks on the earth.
Just open the exhaust valve and check if your spark plug is sparking or not.
If the spark plug sparks, things are fine. But, If it does not spark, it indicates a problem that needs to be handled properly.
In the case of plug misfires, it will start igniting the uncombusted fuel from the exhaust system.
Note that a spark plug helps the ignition process to be successful. If it malfunctions, you will experience incorrect ignition timing along with the compression.
Last but not least, check the spark plug to know whether it is worn out or unable to perform its job anymore.
Jets are very important parts of the dirt bike carburetor. There are four components (jet needle, needle jet, main jet, and pilot jet) of carb you should take care of. If you fail to keep those parts dirt-free, you are likely to experience more backfires.
When it comes to jets, they are very prone to get clogged with a lot of dirt and debris. Often the tiny holes of the jets are blocked with debris. As a result, the efficiency of the carb gets affected negatively.
You might need to use a carb cleaner to clean all the four components so that they can ensure easy and smooth flow of the fuel through the channels.
The low-quality fuel can trigger backfiring in your dirt bike. Though it might save you money, it is not good for your bike for long-term use. Find out the best graded high-octane fuel to avoid backfire.
How to Prevent Backfires in Dirt Bikes?
Keep Your Carb Clean
To avoid dirt bike backfire through the carb, check the carb of your dirt bike regularly to know whether it is clean or not. If it is clogged with dirt, you have to clean it immediately. A dirty carburetor is one of the key reasons for backfire as the engine runs lean due to inadequate fuel supply.
While you buy a carb cleaner, make sure that you choose a high-grade cleaner. Start by cleaning the exterior of the carb first. You might need to remove the housing to clean the jets and the air duct thoroughly with the carb cleaner.
Change the Fuel Grade
Are you using low-quality fuel for your dirt bike to save bucks? If yes, there is bad news for you. Average and low-quality fuel can contribute to the backfire of the dirt bike.
If you cherish getting better performance out of your bike and the engine, you should avoid using substandard fuel.
We recommend you use the high-quality fuel as it will not clog the fuel lines. When the fuel line does not contain any debris, the fuel can pass through it easily and, as a result, the fuel and air balance is preserved.
Clean the Jets
Cleaning the jets is another important thing you should not ignore if you want to get the best performance from the engine and maximize the longevity of the dirt bike. Well, cleaning the jets thoroughly might take time, but the result you will get is amazing.
You can experience better riding with fewer backfires if you clean all the clogged jets from the debris.
We highly recommend you clean the jets every time you clean the carb of your dirt bike. It will help your bike maintain the optimal fuel flow and save your bike from running too lean.
Stop Using Inappropriate Exhausts
Are you using inappropriate exhausts from the aftermarket? Well, this can also cause backfire issues in your dirt bike.
There are many exhausts available out there made for specific models and bikes. But, if they are not customized properly for your bike, you will not get any benefits from those high-performance exhausts.
If your current exhaust is responsible for the backfire, try to replace it with the stock exhaust that the manufacturer recommends for your dirt bike model.
Clean the Air Filter
The air filter condition determines the efficiency and lasting period of the engine. As you explore the off-road and muddy trails with your dirt bike, the likelihood of the air filter getting clogged increases.
How frequently you should clean the air filter of the dirt bike depends largely on how much you use it. If you are not a frequent rider, you can clean the air filter every 3,000 miles or 6 months. If you use your bike most often, you might need to clean the air filter more frequently.
Another thing you should know about the air filter is that they wear out pretty quickly. However, it will not cost you much to replace one as it is not so expensive.
Use Good-Quality Fuel Injector Cleaner
In case your dirt bike is fuel-injected, you should make sure that you have got a high-grade cleaner to clean the dirt so that you can avoid any kind of blockage and lean fuel issue.
Why Does My Dirt Bike Backfire on Acceleration?
Dirt bike backfires on acceleration indicates a problem with the intake system of the bike. If the intake system has any air leaks, it will let too much air enter into the engine of the dirt bike.
The extra air messes up the function of the engine and creates a combustion problem. And it ends in a backfire.
Bad wiring can also be responsible for backfiring. In case the wiring of the ignition system is not correctly hooked up, the combustion system can malfunction.
The problem in the carburetor is another common reason for dirt bike backfire issues in the acceleration. Low compression can help build up the air and fuel and this creates a backfire.
Last but not least, you can also experience backfire due to an issue with the valve springs.
Why Does My Dirt Bike Backfire on Deceleration
Backfire on deceleration occurs when there is excess fuel left in the combustion chamber. A backfire helps the dirt bike to burn that excess fuel.
There are three reasons for dirt bike backfire on deceleration:
- The change in pressure while the exhaust ports open crates a lean mixture of fuel/air. Though the fuel and air still keep burning, the burning rate is slow. When the exhaust transfers the burning mixture to the exhaust system, the mixture explodes even if the combustion process is no more active.
- A deceleration backfire is the outcome of an incorrect air/fuel ratio. If the engine runs rich or there is too much fuel, the combustion chamber becomes unable to burn all the fuel.
As a result, the uncombusted or unburned fuel comes into the exhaust system. This is where that fuel ignites.
When the fuel burns in the exhaust instead of the combustion chamber, you experience backfire when you slow down your dirt bike.
- Low compression in the engine is another reason why your dirt bike backfires on deceleration. If there is low compression, the air/fuel mixture that rushes into the combustion chamber exceeds the burning rate of the fuel.
When the half-combusted air and fuel mixture enters into the system, the backfire occurs.
You can experience backfire for any of the reasons mentioned above when you’re during the deceleration of the dirt bike.
Frequently Asked Questions (FAQs)
When does a dirt bike backfire occur?
A dirt bike can backfire in any of the 3 situations:
- At the time of start-up
- At the time of acceleration
- At the time of deceleration
How does the dirt bike backfire sound?
No doubt, a dirt bike backfire sound is not an enjoyable one. If you hear a sudden growling sound when you are trying to start the bike, accelerate or decelerate, your dirt bike is having the backfire issue. However, it may also sound like a pop or bang.
Why does my dirt bike backfire when starting?
Backfire in the starting of the backfire can occur for any of the following reasons:
- Ignition timing
- Weak ignition
- Applying any throttle while kicking, etc.
How do I know if my engine is running too rich?
If your dirt bike engine runs too rich in fuel, you are supposed to smell the gasoline when your dirt bike runs unevenly or when it is idle.
How can I handle a dirt bike backfires issue?
When you face a backfire on the road, you can make a quick guess about where the problem lies. If you have screwdrivers and wrenches available to you, you can make a quick analysis by checking the engine, jets, air filter, and the carburetors. Check if there are any blockages in those parts that are making your dirt bike backfire.
However, if you are a new dirt biker, you may not have experience with these technical issues. If you are unable to find the source of the problem, you should take your dirt bike to a professional mechanic who can fix and resolve the issue for you.
How can I clean the carburetor of my dirt bike?
When your carburetor is dirty, it is really important to clean it to prevent backfire. Here are the steps you should follow to clean the dirt bike carburetor:
- Buy one or two cans of carburetor cleaner.
- Wash the engine, exterior of the carb, and other parts of the bike.
- Take pictures of every technical part so that you can assemble back the parts of the dirt bike properly after you complete the carb cleaning process.
You might think that you do not need to, but what if you forget about the correct place or get confused about any parts that come with several connections? To avoid the risk of making a mess, capturing some pictures for reference will come to help.
- Remove the carburetor carefully from the dirt bike using your tools. Drop the preserved fuel completely from the float bowl.
- Bring out all the housing and the jets. Spray and clean them by carb cleaner. Make sure that all the parts and holes are clean, free of junk, and debris. If they are very dirty, you can also soak them in them into the hot soapy water to get the dirt out.
- Clean the air filter manually. Also, wipe the air duct out.
- When you are done, put all the parts back to their respective places. If you forget about any parts, take help from the pictures that you captured at the beginning.
That’s it! If you have any issue with the carburetor, cleaning it thoroughly should solve the issue. However, if the backfire problem persists, you have to check if it is an airflow issue.
If you wondered about ‘why does my dirt bike backfire’, we hope that you know the reasons now after reading this article.
There are a variety of reasons that make your dirt bike backfire such as clogged jets and air filter, using low-grade fuel, low compression, engine running too rich or too lean, etc.
Follow our suggestions given above to prevent the backfire in the dirt bike. Enjoy riding!