Why Does My Motorcycle Backfire And How To Fix It

A motorcycle backfires may be something to worry about. Especially, if the backfiring happens every time you ride. I guess the sound scared you so you immediately went to researching. Although this is worry-some for beginners, it’s a common issue for experienced riders. So, why does my motorcycle backfire? Here we will go through the several reasons for a bike backfiring.

Motorcycles will backfire for a couple of reasons. The usual suspects are a dirty carburetor, low-quality fuel, clogged jets, exhaust leaks, bad exhaust pipes, and excess fuel. 

I bet you want to know more about each of these issues, so let’s get into it.

What Happens When A Motorcycle Backfires

We’ve listed the causes of this problem but they all mean the same thing. When the bike backfires, the sound comes from the exhaust pipe. But the issue is not necessarily located in the exhaust pipe. It just means that some amount of the fuel was not combusted properly.

As you can see, all of the causes I listed have something to do with processing fuel. That’s why I want to go through each of these, thoroughly. This is the easiest way to find out why the fuel injection in your bike leads to backfiring.

What Causes A Motorcycle To Backfire

Let’s start right away. I advise on reading the list before checking out your bike. I will also offer answers on how to fix these issues.

Carburetor Issues

Carburetor Issues

For those that don’t know, the carburetor regulates the flow of air in your engine. The air is responsible for drawing the fuel in the engine. Simply put, the carb regulates the air-fuel mixture. So, if there’s something wrong with the carb, it will result in problems with the combustion process.

Now, I don’t believe that your carb is dead, if so, you wouldn’t be able to start the bike. I guess that you have a dirty carb. Believe it or not, a dirty carb is the most common reason why bikes backfire.

A dirty carburetor does not provide the right conditions for the motorcycle engine. It makes for a lean condition engine. This means that fuel flow is not smooth. In turn, unburned fuels will go through the exhaust. So, the exhaust backfires.

How To Clean A Dirty Carb

The easiest way to solve this is to take the bike to a mechanic. But that may not be necessary. You can just buy a carburetor cleaning solvent. Read the instructions on how to use the solution. This will get rid of any dirt and debris in the carb.

Keep in mind, you still may have a faulty carb, not a dirty one. No need to take it to service right away though. Read the whole guide, and eliminate the other causes. If you are still left with the carb, take it to a mechanic.

Bad Air-Fuel Mixture

Another cause, related to the carb, is excess fuel. I would put this into the “Fuel Issues” part, but this is a carb issue as you will soon see. Have you tuned your carb? If so, you may have gotten the mixture wrong. Who knows, you may do it on purpose, to make your bike perform better.

Some people adjust the air-fuel mixture to tweak the performance. For instance, allowing more fuel to flow, can make your bike significantly stronger. But that comes with some costs. Some of that fuel may pass without being combusted. Excess fuel can cause your motorcycle to backfire.

This is easily fixed by adjusting the air-fuel mixture screw on your carburetor. If you already did this, you know how to do it. I guess someone else may did this to your bike, so you may not know about this. We have a guide on how to adjust the mixture, check it out.

Exhaust Pipe

Exhaust Pipe 

Now, the fuel combustion process may be just fine. The bike can backfire even if there’s no incomplete combustion. This can only happen if everything is okay with the bike except the exhaust pipes.

First of all, did you add any upgrades to your exhaust? I know some of you want to make your bike sound deeper. One way to achieve that is to add some changes to the exhaust. If you did that, that may be the reason why you are experiencing a backfire.

Did you replace your exhaust? Replacing the exhaust does not necessarily cause backfiring. If the exhaust you bought is specifically made for your model, you will not have issues. But some people buy aftermarket exhausts. Again, this is done to increase the performance of your bike. Just like the upgrades, this also leads to backfiring.

The problem with all of this is that your bike had its jet settings specifically for the original exhaust. The new exhaust does not go well with the old jetting. So, to fix this, you don’t need to remove the new exhaust. Just tune your motorcycle.

On the other hand, some of you may have wanted a quieter bike. If so, I guess that you bought a shorter exhaust. A short exhaust makes reduces those deep loud noises. But it also leads to bike backfiring. The reason being, there is too much pressure in it, so it kind of farts to relieve the pressure.

To fix this, you will have to change your exhaust. Unfortunately, no fix for this does not involve replacing the pipes. Consider a longer exhaust.

Jet Issues

The carburetor has several jets that control the fuel flow and fuel pressure. The jets are crucial to the combustion process. If these are faulty, you are going to be facing issues more serious than backfiring. That’s why I guess that you may have clogged jet lines.

There’s a way to find out which of the jets is clogged. This is easily done by twisting the throttle and waiting to see when the backfire happens. If it happens while the bike is idling, the pilot jet is clogged. If it happens when you start moving, it’s the jet needle. If it happens while you are accelerating at high speeds, it’s the main jet.

However, there’s no need for this. My advice is to clean all of the jets. It makes no sense to waste time on finding out which of the jets is clogged. To fix clogged jets, get a carb cleaning solvent and jet cleaning tools.

Fuel Issues

Fuel Issues

Since backfiring is caused by fuel that has not been combusted, the problem may be with the fuel itself. You can skip this part if you are sure that the fuel you are buying is top-notch, quality-wise.

I don’t know how familiar you are with the fuel you are using. The fact is, that all gas stations use a different type of fuel. The difference is in how the fuel is processed and made. Some stations may dilute their fuel to make more money.

What I’m saying is that low-quality fuel can lead to backfiring. Low-grade fuel has a lot of components that create dirt and debris when combusted. This will clog the fuel lines and make your gas tank dirty. This, in turn, causes the exhaust to backfire. The pressure gets too high because of all that dirt, so the exhaust blows that out in a burst.

So, did you buy bad fuel? If so, consider switching to a high-quality fuel. Think about this, you don’t save money with cheap fuel because the money you saved, you will spend on repairs. My advice, buy better fuel.

Things To Look Out For

The best way to approach this is by the process of elimination. Chance is, most of you already know what you need to do. If you did anything to cause the problem, you should already know what it is, after reading the guide, of course. Some of you don’t even know why this is happening, so you will have to check everything.

Signs Your Carburetor Needs Cleaning

  • Your bike will start and fail, or won’t start at all.
    If the dirt is too bad, the fuel-air mixture will be too messed up to start the bike or keep it running.
  • Black smoke comes out from the exhaust.
    This happens when excess fuel enters the exhaust ports.
  • Exhaust backfire and combustion stroke.

Signs Of Motorcycles With Lean Mixtures

  • The bike struggles to accelerate.
  • The bike won’t feel as powerful.
  • Bike backfire.

Signs Of Clogged Carb Jets

  • Bike backfire.
  • Black smoke coming out from the exhaust.
  • Starting problems.

How To Fix Motorcycle Backfire Issue

The most common causes of a motorcycle backfire are a dirty carb, bad exhaust, and low-grade fuel. To fix the backfire you either need to clean your carb, change your exhaust, or start using high-grade fuel.

Check out the signs for each of these causes. Is anything else present besides the backfiring? To clean your carb, use grade carburetor cleaner. Cover exhaust leak. Don’t use aftermarket exhaust. Consider using Higher Octane Fuel.

A couple of things you may want to know about though. Running a leak mixture leads to engine damage. So, you may want that checked out by a technician. Using cheap fuel for a while can lead clog your fuel lines, the air filter may be too dirty. Using higher-grade fuel won’t be enough, you may need a technician.

Should I Take My Motorcycle To A Technician

It depends on what caused the backfires. If it was a dirty carb, just clean it, and see if any problems persist. If you have used bad fuel, you should take an expert take a look at it. Have you tried everything and the bike still backfires? That may be a timing problem. I don’t recommend touching that if you don’t know what you are doing.

Related Questions And Other FAQs

Is Backfiring Bad For A Motorcycle

Backfiring can be bad for a motorcycle. Any changes in the fuel ratio can cause damage to the engine block. Regular backfiring experiences are usually not a good thing. If it only happened once, it’s nothing to worry about.

Can Bad Spark Plugs Cause Backfire

Spark plugs can cause a backfire if the fuel mixture is rich. Fuel that has not been burned out in the exhaust ports is lighted up by the spark plug. This causes the exhaust to release a popping sound.