Why is my pit bike smoking and how to solve it?


Pit bike smoking occurs due to many reasons such as worn piston rings, engine running lean, blown head gasket, excessive oil or bad crank seal.

In some situations you will suddenly face this problem and if you keep on using the same bike it may cause unnecessary problems to you and also your bike.

You can repair this problem on your own if you follow my guidelines. Managing this condition differs from different colours of smoke from your bike. Usually three different colours of smoke like white, blue, black or greyish are emitted.

The reasons behind all these vary and I will tell you about that in this article.

Causes of Pit Bike Smoking 

Before going for the solution, know what is actually causing smoke from the dirt bike. Below are a few points which could be helpful to you. 

Piston rings:         

It is the most common reason for emission of smoke from pit bikes. Its usual function is that is separated lubricant oil from air and fuel mixture in the cylinder.

When this function in your bike fails your bike faces a problem of mixing of lubricant and air with fuel generating lot of smoke. This smoke generated from this problem is black in colour.This may be due to over friction between piston rings.

Contamination:             

Usage or mixing up of unwanted oils with combustion fuel causes generation of smoke which is usually blue in colour. If any contaminated substance present within the engine also causes this type of smoke. There is increasing pressure inside the engine cylinder and due to lack of area of expansion.

Bad exhaust gasket:             

When the exhaust pipe is gummed up totally with oil and you didn’t clean it for a long time it may cause release of smoke from it.

Cool temperatures:          

When the surrounding environment is cool,during the first stroke it’s norml to get white smoke but when more and more white smoke is emitting there may be chances of oil getting into your machine.

Power valves:         

Dirty or uncleared power valves are  also the cause of smoke from your pit Normally  the power valves are designed to smoothen the power of bike, they get dirty on usage, so you need to check for power valves once and then clean them.If you do this regularly then your bike will be in good condition.

Air filters:         

A dirty air filter will not allow fresh air to enter into the combustion system. If they are stuck you should clean or replace them.Mostly air filters cause Black smoke.

Different Colours of Smoke and its Meaning:

You will see different kinds of smoke coming out from the exhausting system. Let’s see what it means and causes. 

White smoke:              

The reason for this is very cool and it’s commonly seen.It is normally an indication of water.Reason behind this is condensation of water in the exhaust.

Usually when you start up a dirt bike exhaust starts to warm and when the exhaust system entirely get warmed up it vaporizes all the steam present in it in the form of smoke.

So if you see a white smoke after the start up you have to understand that it is just steam but if you see bouts of white steam coming from the silencer it may be due to other reasons and you have to stop riding it and take your bike to nearby mechanics shop and I make sure if you don’t stop the bike immediately then you will be the reason for the damage of your engine.

If possible check for the leakage of  engine ,there may be chances of engine getting leaked causing white smoke.

Black smoke                   

It is due to over rich fuel mixture. On ignition the contaminated fuels cannot burn and it is pushed out into exhaust system. Hence as the air-fuel ratio is reduced than it is required for  creating spark,it gets combusted in the combustion chamber.

Other reasons may be like blocked fuel return pipe, broken oxygen, air flow sensor, leaking fuel injector or stucking of fuel regulator.

If you have a bike with carburetor you should adjust it or if you have bike with fuel injected, you should check for fuel return line.

Blue or greyish smoke                 

You can most commonly see this type of smoke coming from the dirt bikes. Reason for this is usually mixing of unwanted fuels which combust along with fuel and air.

If it is a 2 stroke, if you don’t know about 2 stroke engine, let me tell you that In this type all the 5 cycles i.e intake, compression, ignition, combustion, exhaust completes in two strokes of a piston and this type of blue smoke is normal as you have oil mixed up with gas, but if yours is a 4 stroke (engine which has all the 5 functions completes in 4 strokes engine) oil getting accumulated behind the piston rings.

Its not like you have to ignore if it is a 4 stroke as it is a easy method to solve the problem.

Usually pistons have rings that enable them to ride up and down and create compression forces, they fail to work when used for a long time and can cause release of such type of bluish grey smoke. 

It is a dangerous situation if you don’t find the leaky points. If oil spillages from any part of your bike the underlying cause may be of burning wires inside the dirt bike ,this leads to a fire accident.

How to Fix White Smoke

You know what causes white smoke, now time to see how to fix it with the following steps. 

  1. Confirmation: 

You have to confirm the white smoke is a steam that comes when an antifreeze substance like water gets burnt in the cylinder.

After confirmation you have to check for the oil, if it is milky it means water is mixed with oil and you all know that that oil doesn’t mix with water but if it is present in the cylinder they get churned together and get whitish consistency.

2. Check for the temperature:           

As the common reason behind the white smoke release is that cool temperatures,you have to first check the temperature and if it is less than 50 degrees of Fahrenheit it’s quite common till you start up your bike.

As I told you before if there is lot of white smoke releasing in spite of  warm ups then possibility of water into engine is more likely.

3. Monitoring:                      

You should regularly be checking your bike’s piston rings, seals and cylinder and confirm their condition.If they are dirty or in bad condition it would be the best thing if you stop using your bike and take it to the carpenter.

How to resolve blue smoke:

You may need to change some parts if the bike is releasing blue smoke. 

  1. Inspect spark plugs:

You should definitely see for the spark plugs if  blue smoke is emitting from your bike and you can confirm the oil and fuel mixture by just looking at the spark plug if there is deposited black soot or black film.

2. Check for Valve seals and piston rings status:                 

If there are damaged rings of piston or dislodgement of seals bluish grey smoke emits and you should tighten them or replace them with new ones. You must thoroughly inspect for the cause as it may lead to fire accidents due to burning wires inside the bike.

How to stop black smoke

Most of the time, it happens due to blockage or damaged parts. Check the following part to confirm which one is making it possible. 

  1. Air filters:                      

The most common reason for black smoke is clogged air filters. Inspect for the air filters regularly and clean them or replace them if they are damaged.Cleaning them also improves the mileage of your bike.

2. Piston rings:                  

As I said above it is one of the reasons for black smoke.So it should be inspected regularly and replaced if they are damaged.

3. Fuel additives:                  

You should use those additives which don’t lower the engine performance. Petrol additive increase octane rating which is the measure of relative ease at which fuel ignites.

Normal range lies within 40 to 55. They act as inhibitors of corrosion and act as a lubricant.Few examples of fuel additives are alcohols like ethanol, methanol, antioxidants like butylated hydroxytoluene, and ethers, detergents,anti knock agents etc. 

But some additives are harmful and are seized in some countries.

Above all change engine oil frequently and give your pit bike for service regularly, exhaust to be cleaned after a run of some kilometres.

Note: Most importantly you have to stop riding the bike immediately.

Only if you have idea about the parts of bike you should start fixing it but if you don’t have any idea the best thing is to take your dirt bike to nearby professional bike repairs.

Just by seeing at the colour of smoke and time at which smoke is ejected you can make your diagnosis and start to fix it.

Conclusion                     

We have reached the end of today’s article “Why does a pit bike smoke?”

I am sure that I have told everything regarding the topic and it can help you with the knowledge of how to fix it.

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Thomas A. Talley

I’m Thomas. Since childhood, I am fond of bikes and hence dirt bikes are my passion now. Ever since then, I’ve been giving advice to the beginners and this has become my hobby.

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