Have you ever wondered how to stop motorcycle exhaust popping, or why does it even happen? Well, it’s a pretty common problem, and most people tend to ignore it.
But if you leave for far too long, it can negatively impact your bike’s engine.
Here, we’ll guide you on fixing motorcycle exhaust popping and saving your visits to your mechanic.
Motorcycle exhaust pop or backfire is a banging sound from our engine exhaust pipe when running your bike. It sounds pretty annoying and can pose a problem to your engine. In addition, it can damage your hearing if you do it in a confined space and even start a fire because some backfires can emit flames.
This issue is a far more common one in those bikes with high-flowing exhaust systems. The excessively hot air that is there can detonate any of your unburnt fuel that might be there in your exhaust. With a detonation, a pop-up sound appears, referred to as backfire or exhaust popping.
A high-flowing exhaust system tends to draw back some fresh air within the system. This fresh air mixes with the unburnt fuel present in the exhaust pipe and combines that hot air.
This unburnt fuel is burning inside your pipe and not inside your engine. So it primarily occurs due to the presence of high unburnt fuel or excessive air within your engine, which can be dangerous and needs to be mitigated as soon as possible.
No, it doesn’t happen in every motorcycle. However, if you don’t do much repair and maintenance to your motorcycle, it will happen no matter what type of bike engine you have.
But backfires are more common in bikes with carbureted engines or those with high flow exhaust systems. There is a case of excessive unburnt fuel in the exhaust system with carbureted engines, while with the engines that have a high flow exhaust system, there is excessive air.
Let’s discuss these scenarios in detail.
Any unburnt fuel in the exhaust pipe is a much more common occurrence, especially if you have an engine with a carburetor. Fuel-injected engines are much better at handling these pops and, therefore, are less common with fuel-injected systems.
It happens because fuel-injected systems have consistently changing air-fuel ratios based on the requirements of the engine. These changes occur due to the ECU, which collects engine data using various sensors in your motorcycle.
Carbureted engines are not evolved to tackle this issue, and they rely on tuning or an auto mechanic. So, whenever you decelerate your bike suddenly, there will be a chance that some fuel left unburnt within your combustion chamber.
This fuel passes through to the exhaust system, and it mostly happens due to the carburetor tuning not being adequately adjusted according to the riding conditions.
Excessive air can also be present in your bike’s exhaust system, and it can result in those pops. This is a more common case with high-flowing exhaust systems. If your bike has a short pipe and a larger opening, it has a high flowing exit system.
Such bikes have robust mufflers to restrict the entry of air that’s coming from the exhaust’s opening. These mufflers are restrictive barricades and prevent excessive air in your exhaust system.
But these mufflers also get weak over time and need a replacement. And when that doesn’t happen, excess air occurs in your system, resulting in backfires during deceleration.
How to stop motorcycle exhaust popping in these two scenarios?
These high-pitched popping sounds are not only annoying to the rider but everyone in the neighborhood as well.
Now, you have to keep in mind that if you have a high-flow exhaust system, you can tune those annoying pops by adjusting your carburetor. Remember we mentioned the word “according to the road conditions” above?
Otherwise, you will have to replace the mufflers in your exhaust if you have a high-flowing system. That is something that you can only manage if you change those exhaust pipes. It can be pretty expensive, and you will also have to adjust other exhaust components accordingly.
For tuning your carburetor, you will have to note down your speed and RPM where the deceleration exhaust popping occurs. After that, you will have to dismantle your carburetor and give it a good clean.
Now you can tune it to get an optimal air-fuel mix. If you have a good mechanical experience with your bike, you can do it independently. Otherwise, it’s a better option to take your bike to your mechanic and get the service done on your carburetor.
So, how to stop motorcycle exhaust popping if there’s some other issue with your bike? There are various other reasons why your bike exhaust is popping. And for that, you will have to determine whether your engine is running a correct fuel and air ratio. When this balance is off, it will be too lean or too rich.
When your bike engine is running too lean, it means that your engine’s air-fuel mix allows too much air to mix up with the fuel. And on the other hand, when your bike’s engine is running too rich, there is not enough air but a lot more fuel in the mix. There will be different symptoms and signs that you will have to see with both problems before fixing the backfire issue.
When your engine is running too lean and has too much air in it, then:
- There will be excessive blue hues in your exhaust pipes.
- With a part throttle, your engine will begin to hunt or surge (RPMs going down and up).
- You will have poor acceleration, and your engine will feel flat.
- Your engine will also begin to run hot as it used to.
- You will get these popping sounds when you decelerate.
- The engine will begin to run better in hotter conditions and not that good in colder weather.
When your engine is running too rich and has too much fuel in the mix then:
- Your engine will have trouble returning to idle without you blipping its throttle.
- Your exhaust will smell like gasoline.
- Those spark plugs will have soot on them, and they will be black.
- Your engine runs better when you remove your air cleaner.
- The exhaust pipe turns back and has soot on it.
- The smoke from the exhaust pipe is blackish.
- You will be getting poor fuel economy.
- Your engine will work better in colder conditions and poor in hotter weather.
- The engine performs worse when it warms up.
Apart from the problem mentioned above where you have a faulty carburetor, or its tuning needs to be done or high flowing exhaust system where you need to repair and replace the muffles or alter other exhaust components, there are some other causes and their fixes as well.
Motorbikes have two different types of timings. One is their electronic timing, and the other one is their condenser setup. Most of the bikes after 1970 came with electronic timing, so things have gotten a lot easier.
With this electronic timing, issues like backfiring can be troubleshot in a much simpler way. But, again, this is because you have to deal with lesser parts. This electronic timing works by sending signals to your bike’s ignition coil when one of your cylinders is in the compression stroke and is about to fire.
These ignition modules work great even if they are 40 years old, so if there is a timing issue, then most likely, it’s going to be some mechanical issue. The timing chain can be another culprit if it has one tooth backward or forward or your exhaust valve if it remains open a bit too long.
For a condenser issue, you have to adjust it according to the instructions provided to you by your repair manual or your mechanic. But usually, you can do it by lining up your timing marks written on the crankcase cover.
When you are done with the timing marks, you will set up the points at specific distances. But this all depends upon what type of motorcycle you have.
Exhaust header is loose
Your exhaust header is the pipe that is connected with your engine. In contrast, your exhaust pipe is the final foot-long pipe that you can disconnect or unbolt. So, we are talking about the exhaust header next to your engine and not that pipe that you and unbolt. This is the area where hot fumes are directly pushed into as soon as they are combusted.
There are threads on this, and this is where the exhaust nut goes. And when this is loose, exhaust escapes from the loose nut and creates a pop. The exhaust gases leaving from this area have a lot of pressure compared to the ambient air, and it can create quite a lot of noise.
Therefore, you need to tighten down your exhaust header. Some headers have bolts, while others have nuts. Some of them also have compression fittings. You will need some help from a welder or your bike shop to fix it, but it will only worsen.
Some motorcycles vibrate a lot while running, which is why their exhaust nuts get loosen over time. Therefore, you need to check your exhaust header every few weeks to ensure preventive maintenance.
It can be a pretty annoying problem because it can be pretty tough to pinpoint. But some signs might help you identify this problem.
Intermittent spark is only going to be an issue if your bike backfires at certain times. These include whether the conditions are too cold or hot or when it is raining or turning left.
This issue arises when your spark plug fires normally, but your engine pops once it doesn’t speak. When there’s air and fuel in your cylinder and that spark plug is not igniting it, it will be pushed out towards the cylinder towards the compression stroke. And as soon as it hits the hot exhaust header, it combusts, creating a pop.
The ignition coil can cause this issue, spark plug wires or the spark plugs themselves. You will have to unscrew your plug from the cylinder and hold its bottom point right against the engine side. You are doing this to ground the spark plug wire and give the spark a way to go.
If you don’t hold it against the engine, it will ground through you and cause a serious shock or burn. So do it only if you know how to do it properly or find a mechanic when you are holding it against the engine block to start the ignition.
If the plus sparks at regular intervals, then it’s just fine, and you can move forwards and check the plug wires. For checking the wires, you will have to purchase a spark tester for your nearest auto parts shops and follow the instructions on how to use it.
You can also quickly check visually of these wires. Inspect them for any frays or cracks, in which case you will have to replace them. And if there is a case of a bad ignition coil, then better replace it and don’t go for any repairs on it.
All exhaust pipes come with their specific installation instructions, and they are pretty easy to install as well. You will have to simply unbolt the old one and slide them right off from the exhaust header side. Then you will have to slide on the new one and bolt it up. However, you will have to go for the correct diameter size of your exhaust pipe, and they will fit pretty well.
It will not directly influence your fuel mileage, but it is a sign that your fuel is not properly converted into energy for your engine to work with. Therefore, your engine average will worsen, but it is not directly because of the popping itself. Exhaust popping is just a symptom that your engine needs an overhauling.
Exhaust popping does not hurt your bike, but your exhaust pipe will discolor with the release of those hot fumes. In addition, these exhaust systems have temperature limits associated with the glasses coming from an engine due to combustion.
Too much high temperature will show its impact, and your pipe will start bluing, oranging, or yellowing as it runs rich or blacking due to it runs lean. There is no other material impact on your bike.
So, is your engine backfiring a lot? Well, now you know what could be the reason behind it. In most cases, it will be the air-fuel mix or the timing is not right. How to stop motorcycle exhaust popping is a pretty simple yet annoying problem. It might not directly impact your bike in the short run, but it can become a major concern in the long run.