Dirt Bike Smoking: 7 Reasons With Fixes (Explained)

Excessive smoke from your dirt bike’s exhaust can depress you. If a dirt bike engine smokes, it’s not working properly. Don’t worry about it, since I’ve identified seven factors that can cause a dirt bike to smoke, and I’ll also tell you how to fix the problem so it doesn’t happen again.

White, blue, or gray smoke can come from a dirt bike engine. Most often, oil burns. A faulty power valve, damaged piston rings, a poor spark plug, or rich gasoline are other causes. Dirt bike smoke can be caused by excessive clearance between the valve guide and valve stem.

A dirt bike’s engine bogging out is one of the problems with the dirt bike, and oil leaks in them are almost always a bother that no one wants and wishes to avoid.

How much two-stroke dirt bike riders should smoke is another common question that is commonly asked, but now we are talking about smoking concerns on a bike, and you can learn different aspects of this.

What is Dirt Bike Smoking?

Smoke from dirt bike exhaust might be caused by piston rings. Piston rings separate lubrication from the air-fuel combination in the engine.

Due to friction, as piston rings wear out, air-fuel mixes with lubricating oil in the combustion chamber, causing bad combustion and smoke from the dirt bike’s exhaust.

Dirt bike smoking has many causes. If we check the bike’s color, we’ll know.

Black Smoke

Black exhaust smoke is caused by the ECU’s equal balance of combustion regulation. A rich fuel combination causes black smoke when the air-fuel ratio falls below the spark’s optimal ratio.

Unburned fuel is pushed out of the combustion chamber and burned in the exhaust system.

Leaking fuel injector, plugged fuel return line, broken oxygen, airflow sensor, or stuck fuel pressure regulator might cause these situations.

Unclean air filters prevent pure air from reaching the combustion chamber.

It restricts cylinder airflow. It reduces combustion efficiency.

Blue Smoke

Blue smoke comes from dirt bikes with oil in the air-fuel mixture. It suggests the cylinders, air, and fuel are contaminated.

This cross-contamination is produced by failed cylinder, piston, and valve seals.

Damaged valve stem seals or guides allow oil to leak from the valve train above the cylinder head.

A damaged piston ring will allow oil from the crankcase to squeeze into the cylinders, but the varying pressures in the combustion chamber throughout the dirt bike will cause oil to be sucked through any gaps, just like air-fuel mixture is sucked in via the inlet valve.

Lack of compression in the cylinders and crankcase pressure can reduce power.

Blue smoke is common in dirt bikes; increasing engine power increases component stress.

Oil seeps If the seals on the turbocharger aren’t working right, the oil used to lubricate the turbine can leak into the cylinders and mix with the air and fuel.

White Smoke

White smoke is possibly steam, which may be nothing or signal an engine replacement a mile away.

When cold, exhaust tips may emit white smoke. It’s harmless combustion vapour.

If your dirt bike is fully warmed up, the temperature is reasonable, and it’s still steaming. Overheating can cause head gasket failure or damaged cylinder heads or blocks.

Head gaskets separate oil and coolant. A split gasket cementing the cylinder head and combustion chambers will leak liquids. Coolant enters cylinders if a head gasket fails.

The engine will try to compress and burn water, causing engine damage and exhaust steam.

The amount of the leak will determine how much steam is created, but when a head gasket fails, you won’t be able to see out the back window.

Why is Your Dirt Bike Smoking: (7 Reasons Explained)

A dirt bike can have smoking issue due to many factors. If you think solving one cause is enough then you are wrong because anytime a different cause will become the reason of smoking.

Having knowledge about every possible cause can definitely help you get rid of this. So here are the 7 possible causes that can make your dirt bike smoke.

  1. Worn Piston Rings
  2. Running rich
  3. Overheating
  4. Excess oil
  5. Leakage in Valve Seal
  6. Damaged Crank Seal
  7. Blown Head Gasket

1. Worn Piston Rings

The piston rings are an extremely important component of a dirt bike. It protects the pistons while also enhancing their ability to perform effectively. If the piston rings are damaged in any way, this could be the cause of various problems.

If you choose to ignore it, it may progress to a more serious stage, at which point it may cause damage to your dirt bike and the cost of restoring it may increase.

2. Running rich

When an engine is operating at a rich condition, the air-fuel mixture being burned will not be optimal. A buildup of unburned carbon inside the combustion chamber may be the result of inefficient burning of the air-fuel mixture.

The amount of unburned carbon in the engine might be detrimental to its performance.

3. Overheating

When riding a dirt bike over hard terrain, the bike could overheat for a number of reasons, including a malfunctioning component or the terrain itself.

The most common reason for this is because the radiator either does not contain any water coolant mix at all or contains a very little amount of water coolant mix. It leads to more smoke being produced as a result.

Temperatures reached while riding a two-stroke dirt bike can range anywhere from 62 degrees Celsius to 82 degrees Celsius (145 degrees Fahrenheit to 180 degrees Fahrenheit), but they can go significantly higher than the point at which water begins to boil.

4. Excess oil

If there’s too much oil in a dirt bike’s combustion chamber, the exhaust will smoke, making the engine run hotter. The oil degrades and leaves deposits on the valves and pistons, which lowers airflow and engine performance.

5. Leakage in Valve Seal

Smoking can be caused by valve seals that are not functioning properly. If the exhaust smoke from your dirt bike continues for a longer period of time than is typical when you start it, the valve seal may be deteriorating. Inadequate sealing of a valve will result in oil burning, which will produce waves of excessive smoke.

6. Damaged Crank Seal

If the crank seal on a dirt bike is damaged, the rider will notice that oil is leaking from his dirt bike. In the event that the crank seal fractures or dries up, this leaves space for fluid to escape. Even a minor amount of leakage might cause accumulation in the engine.

Smoke coming from the engine of the dirt bike is another sign of a damaged crank seal. Overheating the engine while floating over it is the most obvious indicator of oil leaking onto the engine, which can be a dangerous situation.

7. Blown Head Gasket

It is possible for the head gasket to blow on a dirt bike if the bike gets too hot, if the head gasket was not put correctly, or if the head gasket itself failed. All of these scenarios are possible.

The temperature of the dirt bike should be at its optimal level so that it can be controlled. The head gasket might be blown as a result of an increase in temperature, which will cause the dirt bike to smoke.

Smoking in 4-Stroke Dirt Bike Engines:

If white smoke is coming out of the exhaust of the dirt bike, it indicates that there is a leak in the combustion chamber, which is the part of the engine where the gasoline is burned.

Therefore, in addition to gasoline, the engine now burns engine oil. Burning engine oil results in the production of white smoke. It means that you have replaced both the piston and the piston rings in your engine. The piston rings are what keep engine oil from getting into the combustion chamber.

Smoking in 2-Stroke Dirt Bike Engines:

The term “2T” refers to the engine oil used in 2-stroke dirt bikes. The oil and gasoline are combined and then poured into the vehicle’s fuel tank. Therefore, the engine consumes both the gasoline and the oil simultaneously.

If you see white smoke coming from your exhaust, it indicates that the ratio of oil to gasoline in your engine is off, and that you have more oil in your system than is necessary. Always exercise extreme caution when working with the oil mixture.

How to Fix White Smoke in Dirt Bike?

Step 1: Ambient Temperature

First things first, check the ambient temperature of your bike because that has a significant impact on how smoking works. If the temperature is less than 50 degrees Fahrenheit, white smoke will be normal until the engine of the dirt bike has had a chance to warm up.

In the event that the problem with the white smoke continues, it is possible that there is too much water in the machine.

Step 2: Inspect

There is a possibility that the seals, pistons, and head of the cylinder are overheating, which is creating smoke.

Therefore, conduct a thorough inspection of such objects. If you don’t know much about how a dirt bike works, it’s best to ask a professional for help. It’s possible that by doing something incorrectly, you’re making the problem worse.

How to Fix Black smoke in Dirt bike?

Step 1: Air Filters

Sometimes a clog in the air filter may lead to the adequate in your bike’s engine stopping working, which will result in increased fuel consumption. So, this may be one of the things that causes black smoke.

Examine the air filters to determine whether any of them have been clogged and, if this occurs, clean them properly; alternatively, you may replace them if necessary, and, finally, check on them periodically to make sure they are operating normally.

Step 2: Piston Rings

You should perform an inspection on the piston rings of your bike and make sure they are in good shape.

The piston’s main job is to seal off the hole so that engine oil doesn’t get into the combustion chamber of your bike’s engine. Therefore, this could possibly be the reason why your dirt bike is emitting a dark smoke.

Step 3: Fuel Additives

in order to steer clear of the thick black smoke on the bike. By adding the right additives to the fuel, you can lower the performance of the engine and make it use more gas.

How to Fix Blue or Gray Smoke in Dirt bike?

If you see blue or gray smoke coming from your dirt bike, you need to carefully inspect the spark plugs, and if you find that any of them are not in fantastic condition, you need to replace them as soon as you can with brand new ones.

If there is a shiny wet black film on the spark plug of your dirt bike, it may indicate that there is a high mixture of gasoline or air. If there is black soot on the spark plug, it may also indicate that there is a high mixture of fuel or air. Therefore, it may indicate that there is an excess of oil.

Inspecting the valve seals and piston rings to ensure that they are not loose and that they are airtight is something that needs to be done. The blue and gray smoke that you see coming from your dirt bike is sometimes caused by the failure of seals.

Therefore, it is recommended to switch to a new one as soon as you can. If you have no idea what you’re doing, you should either get some help from a knowledgeable person or read the user manual to get some pointers.


Suppose you are riding a dirt bike and you notice smoke coming from it, but you are unsure of what exactly produces it. Therefore, it is best to refrain from riding the bike until it has stopped smoking and is running more smoothly.

If you don’t know how the dirt bike works, you shouldn’t try to fix any part of it on your own, because even a small mistake can cause a big problem. Go to a shop that specializes in fixing dirt bikes and ask them to mend yours in the most effective way possible.