Why Does My Motorcycle Backfire?

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The sound of your motorcycle “growling” is just enough to give you a feeling of satisfaction. This is because the growl is an indication of your engine working properly.

And nothing gives every rider some happiness like a perfectly working motorbike engine. How about when your two-wheeler backfires? What causes it to do so? Let’s find out.

Backfiring on a motorcycle is a common thing that you should always anticipate every time you are enjoying your ride. That said, this issue occurs in the intake or the exhaust of your motorbike. When it happens, it may get you scared, especially if it is your first time to have such an experience.

More often than not, the motorcycle backfire occurs due to uncombusted fuel or gas inside the exhaust pipe.

Motorcycle Backfiring – Causes and Fixes

Here are some of the common causes of motorcycle backfire that you need to know:

1. Wrong Exhaust Upgrades

Sometimes you can be tempted to purchase an aftermarket exhaust to fix on your motorcycle. While this is one way of saving some money on your side, rest assured that this is a wrong move.

An aftermarket exhaust is one of the main reasons why motorbikes backfire. This is attributed to the fact that they are not designed for specific bikes including yours. Instead, they are made to extract more performance. These gadgets rarely work well with standard jetting.

To solve this problem, you need to jet your motorcycle properly. Or you may have it tuned correctly so it can suit the latest aftermarket exhaust. If you fulfill this condition, you can possibly prevent your motorcycle from backfiring due to wrong exhaust upgrades.

2. Faulty Carburetor

If you love racing you must take good care of your motorbike. As such, you should start by checking the carburetor from time to time. This should be the first assignment to carry out every time your motorbike backfires.

You need to understand that fuel cannot flow smoothly through a faulty or dirty carburetor. And if it does, this will lead to a lean-running engine. Consequently, your motorcycle will backfire and even fail to accelerate.

But you can find a working solution to this problem by simply cleaning the carburetor to make the fuel flow through it properly. You may use a high-grade carburetor cleaner to eliminate all debris, leaving a clean passageway for the fuel.

3. Clogged Jets

The carburetor consists of four major components that make your riding possible every time you turn the throttle. But these can get clogged with dirt, preventing them from working properly.

These components include:

Pilot Jet: Its main function is to control the fuel when the engine is idling.

Main Jet: This component controls the amount of fuel when you turn the throttle between 50-100 % power.

Jet Needle: This part of the carburetor controls the amount of fuel flowing through when you close and open the throttle between 20 and 80% power.

Needle Jet: This part represents what the jet needs to take up and down when you turn the throttle between 15 and 60% of the throttle.

To unclog the jets, you need to use a carburetor cleaner which comes fully equipped with a spray can and straw attachment.

Using this type of cleaner, wash every component in the carburetor to open the jets for easy flow of fuel. If you don’t clean these four components, this may result in your motorcycle backfiring.

4. Poor Timing

Different motorcycles come with different types of timing. The two most important timings include the electronic timing and condenser or a points setup. Of the two timings, the electronic one is the most effective when it comes to efficiency and time-saving.

With the introduction of electronic timings a few decades ago, troubleshooting a backfiring problem has become effortless. This is because there are very few parts to check for any fault.

Electronic timing uses a simple working principle. It sends a voltage signal to the ignition coil whenever the cylinder is actually in a compression stroke. This is also the time the same cylinder is about to fire. The entire process is a little bit complex but what matters the most is the timing.

If the timing is wrong, everything else with the engine will go wrong. So if there is a timing issue with your electronically controlled motorbike, it is likely that there will be a mechanical timing problem.

As a result, your motorbike will start backfiring when you are about to start your ride or while on the ride. The same case is true if your motorcycle uses both the points and condenser in its timings.

However, you can easily take care of this problem by setting a point manually using written instructions from the motorcycle manufacturer.

You can also correct the wrong timing by using the repair manual. But this process will depend on the model of your motorbike because these two-wheelers are different in design and mode of operation.

5. Excess Fuel

For the combustion inside the cylinder to take place as required, there is a need for a substantial amount of fuel. Anything less or more than what is necessary can cause a lot of problems in the engine.

Keep in mind that air and fuel have to mix in certain proportions for this process to be successful. Too much air or fuel can hinder the combustion process, leading to serious engine damage.

Sometimes you may hear people claiming that their motorbikes are running rich. This statement means that their motorbikes’ cylinders are receiving more fuel than air.

If this happens, a rich condition may set in and affect the engine performance. This condition may drastically decrease the mile per gallon and slow down your motorcycle. Worse still, this condition can cause serious backfires within the exhaust pipe.

Excess fuel in the cylinder is known to inhibit the ignition process. This is because the ignition will not successfully burn the fuel during combustion. The excess fuel is normally expelled from the cylinder head via the exhaust valve.

As this fuel comes into contact with the hot exhauster header and fresh air, it combusts to create a bang or loud pop sound. This is usually dangerous and scary if it happens while you are on your motorbike.

Luckily, you can prevent such cases by ensuring that there is enough fuel in cylinders for the combustion process to take place. If your motorbike has been at rest for a very time, you should dismantle the carburetor and clean its components thoroughly.

When every section of the carburetor is clean, you can rest assured that the flow of fuel will be smooth for better engine operation.

6. Low-Fuel Grade

Your motorcycle engine is designed to run on high-quality fuel.  This should tell you that you must avoid substandard or low-fuel grades if you want better performance of the engine.

So if you are one of those riders who prefer low-fuel grade to high-fuel grade to save some money, you better think twice. Poor quality of fuel is the main reason why fuel tanks in vehicles end up with dirty gas.

With contaminated gas in your motorbike, you can expect the worst to happen while riding. The dirty gas impacts your fuel injection negatively. In the process, your motorbike starts experiencing backfires every time you try to accelerate.

The remedy for this problem is just simple and straightforward; you should consider using top-grade fuel in your motorcycle and nothing less than that. High-grade fuel will most likely provide you with a cleaner gas tank as well as clear fuel lines.

7. Shorter Exhaust Pipes

As usual, shorter exhaust pipes tend to be troublesome. That is the main reason most states have laws about the length of exhaust pipes on motorcycles. These laws are put in place to prevent cases of motorcycle backfiring.

Short pipes, however, are commonly referred to as shorty and are always 12 inches or less. Their main function is to give a motorbike a cleaner appearance and minimize louder exhaust sounds.

There’s no doubt that shorty exhaust pipes give your motorcycle a desirable look due to its simple small design. But it is a good idea to never choose a shorter than 12 inches exhauster to avoid backfiring.

When they are short, these pipes lack a built-in baffle to reduce loud bags. A baffle is a small part of the pipe that performs the task similar to a muffler in cars. It converts the turbulent flow of used up gas (exhaust) into a more manageable and quiet flow.

Also, shorty exhaust pipes tend to backfire more often because they don’t have enough pipe length to enhance a smooth flow of air.

Designers put a certain length of the exhaust on different models of motorcycles to promote fuel efficiency. With higher fuel efficiency, your motorcycle’s performance improves.

But this comes with risks of frequent backfiring when riding your two-wheelers. To minimize such problems, you should consider going for a motorbike that has a relatively longer exhaust pipe.

Final Thoughts

To answer the question, “why does my motorcycle backfire?”, you need to know the underlying causes of this problem. Mostly, your motorcycle’s carburetor is the main source of backfiring.

These problems may include wrong exhaust upgrades, low-fuel grade, jet clogs and excess fuel among others. Find the solution to these problems and enjoy your ride without the fear of backfiring.

Josh Berry - MotoShark Editor
Josh Berry
I'm a off-road enthusiast, extreme sport fan and the editor of MotoShark. If you have any questions or suggestions regarding this article, please leave a comment or contact me.

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