Motorcycle Exhaust Smoking: 8 Causes With Fixes (Explained)

One motorcycle issue that can get you into trouble and make riding uncomfortable is smoking. I recently overcame this situation by using a workable method and researching all potential causes of motorcycle smoking.

You must study the following eight causes and solutions if you’re sick of this issue and wish to avoid and prevent it in the future.

What is Motorcycle Exhaust Smoking?

A motorcycle can smoke due to worn-out piston rings inside the engine that causes oil to seep up into the combustion chamber.

Motorcycle smoking can also be caused by an external engine oil leak that burns from the heat of the engine, poorly grounded wires, as well as newly installed exhaust wraps that haven’t fully cured themselves yet.

Consider the color of the smoke and whether it is accompanied by any other symptoms that can point to a specific mechanical issue when determining the cause of motorbike exhaust smoking.

Sometimes it’s just the engine’s reaction to particularly harsh weather conditions.

For combustion to occur, a motorcycle engine requires a mixture of fuel and heat that will cause it to burn and produce black smoke.

If it is sooty black or shiny black then the mixture is too rich, which means it is burning too much petrol.

The cause of this could be a clogged air filter, meaning not enough air is getting in to mix with the fuel. Or it could be a faulty fuel injector or carburetor.

Any time you see excessive smoke in any situation, no matter where you are, it should be promptly addressed. Smoke is mother nature’s way of warning us that something isn’t quite right.

Why Is My Motorcycle Exhaust Smoking?

The most frequent cause of dirt bike smoke is an inappropriate air-to-fuel ratio. Oil won’t burn inside the combustion chamber if the fuel is too rich, and unburned fuel will ignite at the exhaust and produce black smoke.

Numerous other factors can also contribute to motorcycle exhaust smoke. Wear-and-tear on the piston rings, improper carburetion, oil leaks, an incorrect air-fuel ratio, burning oil and wires, and exhaust wrap can all contribute to this.

Motorcycle smoking can be identified with the color of the smoke and if this is accompanied by other symptoms that may indicate a certain mechanical problem.

Sometimes it is simply the response of the machine does extreme climatic conditions.

8 Reasons of Motorcycle Exhaust Smoking:

1. Worn-out piston ring:

If your motorcycle is smoking excessively from the exhaust, the first and most common reason, especially among older motorcycles, is due to worn-out piston rings.

Piston rings seal two compartments of your engine away from each other. It seals the top half of the cylinder, which is the combustion chamber, and the bottom half, which is the crankcase.

There are a number of signs of damaged piston rings in addition to smoke, and I have written a specific post to address this problem. Clicking here will take you to an article describing the symptoms of damaged piston rings.

2. Poor Carburetion:

If your bike is smoking a lot and the smoke is black or very dark, you may have a problem with poor carburetion.

In this case, you will notice other symptoms of mechanical failure in your machine, such as the engine bogging down and even stopping while n motion. Visit your mechanic to fix your vehicle.

3. Leaking oil:

Motorcycle will smoke if you have an oil leak and oil is getting onto the outside of the engine and then burning off from the heat.

This will cause smoke that comes directly from the engine itself.

Motorcycle oil leakage is considered a serious problem. To learn more about this topic, click here to read the full article about motorcycle oil leakage and its causes.

4. Air-Fuel Composition:

A problem in gasoline composition may be the cause of your bike smoking if it is an intense white color This may be because the fuel is of poor quality or is contaminated.

In general, we recommend that you always buy quality products for your machine. Even though you spend more, you’re extending the life of our bike.

5. Burning oil:

It can also be because it is burning oil. The color of the smoke is very dark grey if this is the case. To solve this problem, always use a quality lubricant and, if possible, regulate the oil pump as recommended by the manufacturer.

In any case, you should go to the mechanic if your bike has a lot of smoke.

This professional can measure the gas contamination and if necessary, change the catalyst so the problem does not happen again.

6. Climate conditions:

If you live in an area where the temperature is very low, you should not worry if there is excessive white smoke, as this is the natural response of the machine under these circumstances.

Of course, if the smoke is another color or occurs with other symptoms that .ght indicate a failure, go to your mech. ic as soon as possible.

7. Burning wires:

If you have smoke coming from somewhere else on your motorcycle that’s not from the exhaust or the engine, you could have wires burning.

It is the most dangerous type of smoke because it can ultimately start an electrical fire

8. Exhaust wrap:

Another reason a motorcycle may smoke could be due to the new exhaust wrap on the exhaust pipes.

It is a fiberglass-based product that’s wrapped around exhaust pipes for both looks and as a safety, guard to prevent burnt feet and ankles.

How To Tell What The Issue Is By The Type And Smell Of The Smoke

In some cases, it can be obvious where the smoke from your motorcycle is coming from.

It can be difficult in other cases because the smoke may seem like it’s coming from one place but could be from a different source.

If it’s hard to visually see, your motorcycle can help you figure out exactly where the smoke is coming from by what color the smoke is and what the smoke smells like.

Smoke will have a general smell, but these issues previously described will each have an additional distinct smell to them.

White Smoke:

If the smoking is caused by failing piston rings, there will be an excessive amount of smoke coming out of the end of your exhaust pipes.

This will usually be a white smoke with a blueish tint to it. And it will smell like burning oil which is different from the normal exhaust smell.

When you have an external oil leak that’s burning from the heat of your engine, you will again get white smoke with a blueish tint to it accompanied by the smell of burning oil.

These first two should be easily distinguishable since the engine and the exhaust pipe are generally a foot or so apart from each other.

Black Smoke:

Smoke that is coming from the wires of your motorcycle is also very distinguishable.

It will emit a very dark, almost black smoke and will be accompanied by the smell of burning rubber (because the rubber casing around the wires is burning).

If the smoking is caused by new exhaust wraps, you will notice white smoke, almost looking like steam, coming from the entire length of the exhaust wrap.

It emits the smell of burning fiberglass which is quite unpleasant to smell.

How To Fix Smoking Issues

Once you’ve figured out the source of the smoking on your motorcycle, you’ll probably be left wondering how to fix it.

A lot of these issues can be fixed yourself if you have a set of basic tools and are willing to do a little bit of research.

Click here to see my list of recommended tools.

1. Compression Test on the Engine:

It can be a little tricky when you’re dealing with failing piston rings inside your engine. You can start by doing a compression test on the engine. This tests the pressure inside each cylinder separately and if the pressure is low in one or more cylinders that likely means you need to replace the piston ring.

Unless you’ve done this before, this is the one fix I recommend you take into a shop and have them do.

2. Inspect the gaskets

If you suspect your motorcycle smoking issue is coming from an engine oil leak, you either need to change the gaskets and/or tighten the bolts. It is possible to change the gaskets yourself, but you’ll need a little experience to accomplish this. For further information about how to change the gaskets on your motorcycle engine, see my other article here.

3. Tighten the bolts

If you are going to tighten the bolts on your engine, look in your owner’s manual (or you can probably look it up online) and tighten the bolts up to the proper torque specs.

Or you can simply take it to a mechanic and have them re-torque the engine for you.

You mustn’t free-hand the tightening of the bolts on your engine. This can either lead to further oil leaks or ultimately crack parts of the engine from tightening bolts too tightly. I’ve made this mistake before and it’s not worth it.

Do your research first.

4. Check the wiring

If your wiring is your issue, inspect all the wires on your motorcycle to determine which wire is the problem.

Immediately replace that wire and be sure to splice it properly to prevent problems in the future.

Also, ensure that a particular wire is correctly grounded and that it is protected by a fuse.

Also, make sure it won’t rub up against anything such as the front or back tire.

5. Wrap the exhaust Pipes

Smoke coming from exhaust wraps should resolve itself after a few hours of riding.

If you’ve noticed it is not stopping, you may need to rewrap the exhaust pipes and be sure to get them wet first and install them tightly.


It is normal for some smoke to come out of the end of the exhaust pipes. Motorcycles don’t have a catalytic converter that converts exhaust fumes into non-noxious gases. This will in turn cause a little more smoke to come out compared to other vehicles.

With that being said, there should not be an excessive amount of smoke coming out of the exhaust.

Only enough to notice it a little bit. The smoke should also be faint white. In colder months the exhaust will be much more noticeable because of the cold temperatures.

Aside from this, there should be no other smoke coming from any other parts of your motorcycle.

If this happens then, you need to get to the root of the problem and get it fixed without delay.