Why Your Motorcycle Is Smoking and How to Fix It

Why is your motorcycle smoking so much from its exhaust all of a sudden? There could be several reasons, and the key lies in the color of the smoke.

When people find their bike excessively smoking, they’re usually taken aback and scared. But often, you have a leaky coolant or engine oil. Other times, the problem could be more severe, like faulty wiring, broken head gaskets, and warps pistons.

Regardless, there’s no point in worrying. You must take action now and figure out why your motorcycle is smoking. Then, you must fix the issue. Depending on the issue, you may need to call in a mechanic or take your bike to the local dealer.

But all of that comes later. Right now, you must pinpoint the exact cause. And that’s what we’re here for.

Here’s an in-depth guide on what causes smoking in your bike and how to fix it.

Causes of Motorcycle Smoking:

Old Piston Rings:

Old motorcycle piston

Is your motorcycle smoking excessively from the exhaust, more than it usually does? You could be dealing with deteriorated piston rings. The piston rings are essential parts of the motorcycle that transfer heat away from the pistons, blazing hot.

If, however, the piston rings have been exhausted and lost their conductivity, then your pistons may be overheating. This could be a significant reason why your motorcycle is smoking.

Oil Leak:

Oil Leak from engine

So, old piston rings lead to oil leaks. But do other oil leaks also cause the problem? Yes. Oil from your engine, when leaking, will enter the combustion chambers and will start to combust instead of the actual gas. This not only results in lower gas mileage but also generates a lot of smoke.

Faulty Wiring:

Faulty Wiring of motorcycle

Can the smoke coming out of your motorcycle be from an electrical fault? While the chances are slim, it could be possible. Luckily, faulty wiring smoke is easy to identify since the smoke will smell like burning rubber.

Sometimes, the issue is easily fixable, such as when the wires have broken. You can reconnect the cables and use a shrink wrap on them.

If the fault in the wiring is a lot more permanent, however, like melted wires, you’ll need professional help. You should immediately stop using your bike, as you never know what essential components the wires have melted off from.

Newly Installed Exhaust Wraps:

Exhaust wrap

Did you get exhaust wraps installed and started noticing excessive smoking from your bike? Then they could be the culprit.

Despite being rare, newly installed exhaust wraps to make deep sounds can cause smoke to come out from your bike. This is usually the case when they haven’t been appropriately cured.

What Does White Smoke Mean in Motorcycle?

White smoke of motorcycle

What causes white smoke to come out from your motorcycle’s exhaust? White smoke usually means that the coolant is starting to combust along with the gas. This is when leakage in the cylinder or the seals has busted, resulting in coolant leaking into the engine.

One of the easiest ways to diagnose this problem is to check the coolant level in your radiator. If the coolant seems incredibly low even though you recently filled it up, you could have a leakage somewhere.

Another way to diagnose the problem is to have a look at your oil. If your oil has started to brown, then this means your coolant is leaking from somewhere.

However, keep in mind that white smoke is perfectly normal if the ambient temperature is below 50 F. This is because your engine is warming up.

How Do You Fix White Smoke from A Motorcycle?

So, now you know why your motorcycle is smoking. But how do you fix it? The first step is to identify the problem. Is your coolant leaking, your oil leaking, or your engine cold? Let your engine warm up and see if the problem persists.

If it does, check the oil reservoir. If there’s too much oil, then drain out all the excess. This could be going into the engine and burning up.

If the problem persists, then you have a leakage. The main hurdle here is identifying where the leakage is. The radiator cap, the cylinders, or the pipe that carries the coolant could be in the radiator.

Check the hose for apparent leaks. Look under the radiator cap to make sure it’s not broken. Check the gasket underneath the cap along with the O-ring to make sure they’re intact. If not, replace them.

Next, check the cylinders and the head gasket. If any of them seem to be broken, warped, cracked, or otherwise leaking, then you have a more significant issue at hand. You’ll need to contact your local dealership or repair shop for this.

What Does Black Smoke Mean In Motorcycle?

Black smoke of motorcycle

Do you notice black or dark grey smoke coming out of the exhaust on your motorcycle? A few things could cause this. The number one reason why your motorcycle is smoking is a clogged air filter. But a bike that has been jetted too richly will also produce black smoke.

Jetting refers to adjusting the fuel-to-air ratio in the engine to optimize it. While it may sound like a positive thing, too much optimization can damage the engine. And it can lead to black smoke.

But it’s not the only reason. If your air filter is clogged, then this can also lead to black smoke. The fuel injector line could also get clogged, resulting in black smoke. If that were the case, you’d immediately notice it since your bike’s gas mileage would go down.

How Do You Fix Black Smoke from A Motorcycle?

To fix this, you must first identify the problem. Start by taking a look at the spark plug. If you notice any grey smoke coming from the spark plug, this may suggest that the jetting is too rich. Moreover, if you notice a layer of black soot on the spark plug, then you need to tune the jetting down a bit.

However, you see a wet black film over the spark plug; then your engine has excess oil. If that’s the case, drain the extra oil and remember not to fill too much oil in the future.

So that, if there’s nothing wrong with the spark plug, then move on to the air filtration unit. Check if it’s clogged or broken. If it’s blocked, use any suitable tool to unclog it. If it’s broken, you may need to have it inspected for repair or get it entirely replaced.

What Does Blue Smoke Mean In Motorcycle?

Blue smoke of motorcycle

Found your motorcycle emitting blue smoke? Most probably not because it’s hard to identify. Blue smoke isn’t completely blue. It’s usually white or grey with a slight tinge of blue. Nevertheless, you should troubleshoot it much like any other smoke.

Your motorcycle is smoking blue because the engine oil is burning in the combustion chambers. This is usually when your piston rings are not fully sealed, and some oil can leak through them into the combustion chamber.

One way to diagnose this problem is to check the engine oil level. If it is quite low even though you recently refilled it, you have a problem with oil leakage.

Bad glow plugs on diesel engines can also cause blue smoke. You can diagnose the problem by hooking up the battery and seeing if you get a reading from them.

How Do You Fix Blue Smoke from A Motorcycle?

So, how do you go about fixing the problem? Depends on what causes it. If you find that your bike is emitting blue smoke due to oil leakage, you’ll have to identify the location. Then, you’ll have to seal any cracks and replace any broken gaskets.

Take a look at your head gaskets. These gaskets can cause a lot of oil and fuel to leak into the combustion chamber if they are faulty. You’ll need to replace them immediately.

If the piston rings are faulty, you’ll need to replace them too. The same procedure follows when your glow plugs are bad.

Unfortunately, you cannot fix blue smoke without replacing components. And if you’re unlucky enough to have bad glow plugs, head gaskets, or piston rings, you’ll be looking at up to $7,000 in repair.  If you’re lucky, though, you’ll have to replace a few broken gaskets and O-rings.


How Much Smoke Is Considered Normal?

It’s quite hard to provide an exact estimate, mainly because there are not many ways you can measure smoke. But you can get a rough estimate. It’s normal for bikes to smoke a bit more on a cold start than they normally do. Once the engine is warm, though, the smoke shouldn’t be too excessive.

What Is the Reason for Black Smoke on The Bike?

There are two primary reasons why your motorcycle is smoking black: a clogged air filter and an engine that’s running too rich. A third, rarer reason could be that the fuel injector line is clogged.

Is White Smoke from Exhaust Bad?

Smoke that is transparent or very slightly white is normal. But if the color is the smoke is too white, it could mean a potential oil leakage. Anything from your radiator cap to your head gaskets and pistons could be faulty.

Can Low Oil Cause White Smoke?

The short answer is, No. Low oil does not cause white smoke. The oil that gets into the combustion chamber may release what appears to be white smoke but with a slight blue tint.

Why Is My Engine Smoking but Not Overheating?

If your engine is producing a lot of smoke but not overheating, then some fluid (oil or coolant) has found its way into the combustion chamber. Even transmission fluid and condensation on the inner walls of the cylinders can create a lot of smoke.

Can A Bad Fuel Injector Be the Reason for White Smoke?

Yes, defective fuel injectors can be the reason for white smoke. The fuel injector is what administers fuel into the combustion chamber. A permanently open fuel injector or leaking will cause more fuel to get combusted, resulting in white smoke.


A bike that’s smoking is extremely scary. It may lead to permanent engine damage, an unsafe ride, and bad gas mileage. But not to worry. Now you know all about why your motorcycle is smoking and the right steps you can take to fix it.

To conclude, a bike that smokes excessively may have problems with the air filter, the fuel injector, the jetting, and even the transmission. It all comes down to the color of the smoke and a few other factors.