Top 4 Reasons of Motorcycle Smoking & How to Fix It!


Finding your motorcycle heating up and emitting a big cloud of smoke is not a good sign. It may look kind of cool from a distance, but it is the last thing you want coming out of your motorcycle.

Why is my motorcycle smoking? The most common causes are deteriorated pistons, external oil leaks, badly grounded wires, or freshly installed exhaust wraps.

Most bikers will face this problem at least once. The solutions mentioned below can save a bike from severe damage if one knows how to find the problem’s source and fix it. Naturally, it can also save you a good sum of money you’d otherwise pay to a mechanic.

Causes of Motorcycle Smoking

Ignoring significant amount of smoke can lead to further damage to the engine. If there is smoke coming from a bike, it must be addressed immediately.

A smoking bike means a faulty engine. The engine is not running correctly. It also means the fuel in the tank is not entirely burned, with most of the oil evaporating into smoke.

Driving a smoking bike is never a good idea, and it could also endanger the rider’s life. Moreover, it can also be embarrassing to many after showing off their motorcycle only to find it smoking.           

Deteriorated Pistons

If the smoking is excess in amount and coming from the exhaust, then old piston rings are the primary suspects. In a motorcycle, the role of the piston rings is crucial. Its job is to transfer the heat from the hot piston to a cooled cylinder wall inside the engine. The heat passes through the piston ring to the cylinder wall, where it gets transferred to the engine’s coolant.

In the scenario of a set of exhausted piston rings, the oil begins to leak into the combustion chamber. Riders will notice an unusual amount of oil being used up by the bike. It will be seen that instead of the gas, the oil is combusting after going past the faulty pistons. This leads to the motorcycle producing extra smoke.

External Oil Leaks

The next common reason as to why your motorcycle is smoking could be a possible external oil leak. When there is an oil leak, it can enter the engine, causing the motorcycle to overheat and emit smoke.

Most of the time, old motorcycle parts can develop this issue. Old cylinders leak oil, which can be easily located by their seals. These leaks may start small but can progress quickly to a massive leak. This is a problem that can quickly get out of hand and lead to severe engine damage.

Badly Grounded Wires

There’s a lot of crucial wires rigged to a motorcycle engine and gauge. However, any wrong wiring arrangement can pose a dangerous risk to both the rider and the motorcycle. Having wires that are broken, not secure, or melted can lead to a severe electrical malfunction. Such things can lead to the inner structure or the electrical system of the motorcycle to catch fire.

Usually, too much heat in the system or accidents can lead to the wires getting damaged. Sometimes, some wires touching the metal frame of the motorcycle can lead to a short circuit and cause an electrical wire to break out. It can be easily detected with the smell of the burnt rubber. This kind of problem needs to be fixed without much delay.

Freshly Installed Exhaust Wraps

Although it is a rare occurrence, sometimes a fresh coat of exhaust wrap can cause some smoke. This happens if the rider has not fully cured it before using the wrap.

Exhaust wraps are often used to keep the engine temperature low. It helps keep the heat focused on the pipe rather than letting it spread to the entire motorcycle. Too much overheating of the motorcycle can lead to the piston shutting down completely. The motorcycle engine is then destroyed for good and can no longer work.

The exhaust wraps harden by burning, which is good. There is nothing to worry about in this case. They are useful for protecting a rider’s feet and ankles from burning.

Finding the Main Cause of Smoke

There are various ways to identify the place the smoke is coming from. Most of the time, it can be easily found through the smell or the appearance of the smoke. Certain smokes have a distinct smell, and they can easily deceive one’s eyes by leading the rider to the wrong source.

If one sees an excessive amount of white smoke with a little bit of blue hue to it attached with a smell of burning oil, then its source is probably deteriorated piston rings or old valve seals. It can also indicate an oil leak.

To understand the difference between the two, you can quickly check the location of the smoke’s emergence. Is it coming from the engine or the exhaust pipe?

If it is coming from the engine, it means there’s something wrong with the piston rings. If it comes from the exhaust pipe, then there is an oil leak on the engine’s exterior where the oil is being burnt off.

Bluish smoke can also mean the engine’s spark plugs getting mixed with air mixture in the cylinders. This can be found from a thick, dark layer of oil on the plugs itself.

The emission of gray smoke can happen due to the fuel being too rich. It can also occur due to a clogged air cleaner. This kind of emission is dangerous. It would be best handled by a professional rather than fixed at one’s home.

White smoke often means something that has to do with water. This can also be due to the temperature of the air being lower than fifty degrees Fahrenheit. If the weather temperature is lower than fifty, then the smoke is nothing to worry about. However, suppose the smoke persists at that temperature after the engine has warmed up. In that case, it is due to an excess amount of water in the engine that can lead to white smoke.

Problems in the composition of gasoline can also give out white smoke. This is often the warning for feeding the motorcycle with contaminated fuel or just fuel that is of bad quality.

Cheap fuel is never a solution. The motorcycle will eventually break down and give the rider an additional cost of buying another motorcycle. Premium quality fuel extends the life of a motorcycle. The emission of white smoke is usually rare. Therefore, having a professional deal with it is very much advised.

If one sees a large amount of dark and black smoke, it could mean that there is a failing carburetor. The job of a carburetor is basically to mix air with a spray of liquid fuel. This forms an explosive mixture that can be used in the internal combustion of the engine. The failing carburetor will also be indicated by a bogging engine that occasionally stops in motion. Burning wires can also produce black smoke, often accompanied by burnt rubber’s distinct and unpleasant smell.

How much smoke is too much?

Motorcycles always have a little bit of smoke being emitted constantly. The question is how much smoke is too much smoke. The limit lies somewhere, and therefore, it is crucial to understand where the line is eventually drawn. Once one gets used to riding a motorcycle, they develop a calibration of their own to detect what amount of smoke emission can be considered normal.

To begin with, the apparent smoke coming from your exhaust pipe is normal. Motorcycles tend to give out more smoke compared to other vehicles. This is because they have no space for a catalytic converter, which is a crucial device. A catalytic converter converts the hazardous gases and harmful pollutants in the gas emitted by the exhaust from the motorcycle’s combustion engine into harmless gases. Due to its absence, motorcycles generate more smoke than usual.

However, if there is too much smoke coming from the exhaust, especially if the color of the smoke is white, it is abnormal. This usually happens in regions of lower temperature, which is not something to worry about. However, suppose there’s excess smoke coming out in areas with warm climate. In that case, it is best to get it checked by a professional.

Solutions for Smoke

There are various ways to fix a motorcycle smoking. The first step to fixing it is to immediately pay attention to the motorcycle and not put it through any further strain.

The next step would be to grab a few essential tools to help one through the process. There are primarily five tools that every motorcycle rider should own:

  • A vise grip wire stripper and cutter to handle the wiring problems.
  • A socket and wrench set to help through most of the difficulties a motorcycle might face.
  • An angle grinder to customize your motorcycle.
  • Channel-lock pliers are adjustable tools that help in fixing a motorcycle.
  • A motorcycle lift to help with making the physically strenuous task of fixing a motorcycle a bit easier.

When it comes to a situation of deteriorated or worn-out pistons, one needs to be careful. It is a difficult situation and requires a set of dexterous skills in machinery. If one has no experience handling heavy mechanical work, then the following set of instructions should be done by a dealer.

First off, a compression test is required to be done on the engine. The pressure inside each cylinder is tested separately. If the pressure measured is too low in any of the cylinders, then it’s a sign for the pistons rings to be changed.

If an oil leak is the suspect, then you need to tighten the bolts with a wrench. The bolts should be screwed up to the exact and required torque specs. Tightening them too hard could cause some parts of the engine to crack or increase the frequency of oil leaks. It is best to read the motorcycle’s user manual before getting to the job—another way to fix this issue to replace the gaskets. However, replacing gaskets needs a bit more experience from the rider, so it is best to research it before handling it alone.

The other possible problem left is the case of bad wiring. This is a hazardous situation, and the person fixing it must keep in mind to stay safe. Make sure to inspect all the wires on the motorcycles to find the broken or melted wire.

Once the wire in question has been found, check if it has been correctly grounded. It is also crucial to see if it is connected to a fuse. This step is vital because if it is not done, the current will flow through you and induce an electrical shock.

A motorcycle deals with a large amount of voltage, and such an accident can lead to death. When the precautions are done with, change the wires and splice it so that it doesn’t bug you in the future.

Smoke from exhaust wraps is expected, as mentioned before. However, a poorly wrapped exhaust pipe can cause the smoke to persist. One possible way out is to get the wraps wet first and then install them tightly enough to not show any smoking problems in the future.

So I hope this helps you resolve the issue. If you have any questions or more tips feel free to chime in with a comment below! 🙂

Luka Barron

Motorcycle mechanic, writer and Heineken lover. A bit like Hank Moody on a Suzuki.

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