Why Is My Motorcycle Exhaust Smoking? Troubleshooting Tips!

Why Is My Motorcycle Exhaust Smoking? Troubleshooting Tips!

There are several major causes of why your gear might be smoking, but it’s nothing to be embarrassed or worried about, as these can easily be fixed if you know just what to do.

Motorcycles are much simpler than you might expect, and fixing the problem that’s plaguing your bike through a process of elimination is usually not that difficult. There are several ways to address this problem.

However, it is best to fix it as soon as the problem arises, as it can pose a safety risk down the line. This article will help you troubleshoot your bike to find and solve any possible damage that may end up creating smoke.

Why is my motorcycle exhaust smoking?

The excessive smoking of motorcycle exhaust can be due to three key factors: oil piston rings, oil leaks, or faulty wiring. When it comes to old motorcycles, it's mainly due to worn piston rings, which allow oil to enter the combustion chamber and block it up.

What Are the Reasons for an Exhaust to Smoke?  

Smoke coming out of your motorcycle exhaust is an extremely common occurrence, and you might be dismissive about it.

But when excessive smoke is created, it’s usually a sign of an error in the system which you should promptly have a look at, especially if it’s a rather old bike.

An Exhaust to Smoke

There are, however, three major reasons that result in excessive smoke. With old bikes, it’s usually because of the exhausted piston rings that can push the oil to enter the combustion chamber and clogging it up.

1. Old Piston Rings

The piston rings seal the top of the cylinder, where the combustion chamber stores the fuel/air mixture and the bottom on the crankcase.

And the oil that splashes the bottom of the piston is supplied from the crankcase, which keeps all the parts well lubricated. But if that oil reaches the combustion, past the piston rings, it can lead to your engine overheating.

Once the gas starts combusting instead of the oil, the crankcase soaks it up much faster and overheats. However, this is a very common occurrence, especially if you use your bike for a daily commute.   

2. Oil Leak 

Another similarly common reason for excessive smoking is an oil leak, which can often seep out of the internal system and onto the engine itself, effectively overheating and getting burned off.

The oil usually leaks from the cylinders, and you can easily find it once you locate the seals on the cylinders, and they are separated into different parts. So, it’s best to check all the seals for any leaks.

3. Faulty Wiring 

Another reason for the smoke could be faulty wiring if the smoke isn’t coming from the engine or exhaust. This is a rare occurrence, but it still can happen under some circumstances.

However, this type of smoke needs to be dealt with as fast as possible, or it can lead to an electrical fire from the burning wires.

It’s best to identify this problem by checking if the wiring carriage has any visible burns or scorch marks. And it is usually warranted by the smell of rubber burning away from the wires.

Identifying the Problem 

This can also lead to melted plastic, which can cover other parts of the engine and become more difficult to solve. Make sure you don’t turn on your bike in any way before this issue is fixed. Excessive smoking from uncured exhaust wraps can also take place, despite being a significantly rare occurrence.


If you’ve applied a new coat of exhaust wrap, it’s recommended that you wait a day or two for it to be fully cured before using it. The fiberglass used to wrap the exhaust tends to burn in order to harden.

Motorcycle exhaust heat wraps are great for enhancing safety and appearance, but once you’re done applying the coat, an unpleasant stench is warranted while it absorbs the heat from the engine.

What Does the Color of the Smoke Indicate? 

Just like there are different parts that can be affected to cause your exhaust to smoke, you can also determine the problem from the color of the smoke.

The Smoke Indicate

Blue Smoke 

Blue smoke is a result of spark plugs being contaminated with a rich fuel/air mixture from the cylinders. This is indicated by a shiny and black layer of excess oil on the plugs.

Worn out piston rings or valve seals results in the oil from leaking out of the cylinder, which also causes blue smoke.

Gray Smoke 

Gray smoke can happen from the fuel/air mixture being too rich or a clogged air cleaner. And gray fuel is much more dangerous to your machine than blue smoke, which is why it’s best to talk to a professional.

The solution to gray smoke can either be a new air clear or learning to make the mixture leaner for your gear to handle.

White Smoke 

White smoke is a product of excess water buildup, which is why it’s best to make sure that the air temperature is below 50f when you encounter white smoke.

Remove any excess oil from the oil reservoir, the exhaust continues to smoke as the engine burns more oil. White smoke is much rarer, which is why it’s recommended for the user to consult the local dealer.

Locate the Problem of Your Motorcycle and Get It Fixed Today!

Even with the best aftermarket motorcycle exhaust, maintenance is always required. Although, excessive smoke might seem daunting at first glance, it’s certainly nothing to stress about, especially if you know your gear!

Follow our guidelines and learn to solve any problem that might arise in your exhaust at a moment’s notice!

joshua mattie

Joshua D. Mattie

My motorbike addiction began with 50cc at 5 years old. I rode motocross as a teenager & into my 20's when I worked as a mechanic. This helped me to see the light—sportbikes & cruisers became a passion. Now I'm building BikersRights to be the #1 resource for everything on 2 wheels!