Why your dirt bike won’t start – (12 Possible Problems and their Solution) ?

Dirt bike starting issue is a type of problem which can happen to any dirt bike at some point of time. This problem can be very much frustrating when you are trying hard to start your bike but your bike won’t start. So I decided to do some research why does your dirt bike not start and here is what I have learned.

Dirt bike won’t start if gas is old and vernished, gas is not turned on, choke is not on, carburetor is dirty, bike has low compression, leak in intake air, bad kill switch, spark problem, battery is dead, bad tuned carburetor jetting or air filter is dirty.

Dirt bike starting issue can create a huge trouble when you plan to go for a relaxing ride then you find it dead and it fails to start eventually. You should go through a checklist of probable causes for dirt bike starting problems. If you want to learn some procedures of diagnosis of your dirt bike then you are at the right place.

In this post, we will discuss about the basics of why any dirt bike won’t start and things to do when dirt bike is not starting. So that you can restart your dirtbike again! If you have not started your bike for a very long time or the dirt bike is been in storage for in garage for 2-3 years.

Procedure of starting :- for the starting of any dirt bike, it just needs a spark in the engine and a proper mixture of air and fuel in the combustion process. If the mixture is not combusted, the spark will not be generated.

You need to take care of each and every part of your dirt bike to know the reason of the issue. Right steps should be taken to spot the issue. Try to solve the issue as early as possible. Turn on your gas in Tank, For checking the issue. Check the gas whether it is old or varnished.

Clean the carburettor if it is dirty, low compression, intake air leak, broken switch, fouled spark plug, dirty air filter, dirty fuel injector aur clogged fuel injector. let’s read them in detail:-

Common reasons why your dirt bike won’t start?

Here are the most common reason who doesn’t a dirt bike start.

  • No spark
  • Battery is too weak
  • Carburetor is dirty
  • Air filter is dirty
  • Fuel injector is clogged or dirty
  • Intake air leak
  • Badly tuned carburetor jetting
  • Low compression
  • Gas isn’t turned on/no gas in tank
  • Gas is old and varnished
  • Choke isn’t on/not working properly
  • Spark plug is fouled
Why is my dirt bike not starting?

1. No spark

Everything is fine but still your bike won’t start then it can be due to the lack of spark. Here is the method to find out this issue.

First step is to remove the spark plug. Coonnect with its cap and let it be rest at the engine. Now kick the lever but before take your bike to a dark place by turning off the lights. While kicking you can see a small blue color spark generated during the kick. But in condition it has zero spark then definitely the bike is not going to start.


To Fix a dirt bike which has no spark, you have to remove the spark plug from the cylinder block, then you need to put it back to the ignition coil and kick start the bike to check the spark. If there is no spark then finally replace the spark plug with new one but after that check all other electric parts..

2. Battery is too weak

Dirt bike which is made to work with electric start have a battery which supplies power to the starter. Battery with low charge is not able to supply enough power to start the engine.


If your bike is not starting and the reason is a low power battery then there are two ways you can fix it. First try to charge it and if it is stillnot able to generate the enough power then you need to replace the old with new one. If you don’t ride your dirt bike regularly, it can be the issue of battery damage. it will give you amazing result with consistency and it also last long.

Compressed air and carb cleaner are the best friend of dirt bike riders. To clean the carburetor loose its clamp, rotate it and spray the jets. This process will not take much time and it can be done in few minutes by removing the float bowl on the bottom of the carburetor.

If this still not helped ypou then you go for thorough cleaning. Take the carburetor completely off from dirt bike and disassemble it. Clean it’ every corner and make sure to clean it properly.

3. Carburetor is dirty

Sometime dirt bike doesnot start normally and it may be due to the dirty carburetor. There is a couple of methods that confirm your carb is dirty. Often carburetor, jet and passages can be dirty because of old gas remaining in it. Even you can see through but liitle bit of crud stuck on it which stops the proper gas flow which results into no start.


Use quality gas for your dirt bike that will run your bike better and it will not cause problems frequently and will help you for long run. whenever you are goin to fill the gas look for good quality. No oxigeneted and no ethanol gas work very well for bikes.

4. Air filter is dirty

You need to check the air filter how dirty it is? If it has a layer of dirt, mud and sand only one of these can create trouble for the bike, that will not let the bike run. Clean the air filter and try to start the bike. To maintain a healthy engine you need to take care of air filter propelry. Dirt air filter make hard for your engine to work and cool down. Allowing clean air in to your engine which combines with fuel and generate power is important.

Fix: Thorough cleaning of air filter is only required in case it is dirty. It is advised that dirt bike regularly runs on sand dunes and muddy tracks so clean it after every heavy ride. For cleaning t remove the air filter and use a cleaner. Use a faucet or garden hose as a rinse from the inside to stop pushing of dirt to fiber of the filter. Then dry it with air and before oiling it make sure it is completely dry.

5. Fuel injector is clogged or dirty

Your dirt bike engine will not be able to produce enough power to run your dirt bike if it does not receive the proper ratio of air fuel mixture. There are many cases of clogged or dirt injector which cause no start. If the fuel injector is clogged or dirt it will not inject the fuel properly.


When a fuel injector is clogged then it needs a concentrated cleaning in order to make it work properly again in better condition. You should contact a ualified mechanic for this job. Can’t you clean this yourself? Yes of course you can clean but I would still say clogged fuel injectors need a qualified mechanic. But if your are very well known with this you can do it yourself.

6. Intake air leak

Dirt bike is not going to start easily if there is an air leak in the system. You need to check the system for cracks including the nut, bolts and gasket assembled between the carburetor, airbox and engine. This air leak causes air to dilute the fuel and oxygen. Diagnosing the air leak is not an easy process it is the most difficult task.


If you find the cracked intake boot then it is easier to replace. Replacing an intake boot is cheaper.

7. Badly tuned carburetor jetting

Jetting is critical in dirt bike carburetor and hence it is important to understand working of carburetor tuning for engine’s optimum working. Air density keep changing which depends on atmosphere. When temprature change it affects the performance so engine carburetor jetting is tuned in such way it can balance the working in such condition. When temperature increases air density decreases and when temperature decreases air density increases. Same way when engine’s operating altitude increases air density decreases because of decreasing air pressureand vice versa.

Earth is very large and atmospheric conditions are always changing so you can understand it is impossible to setup a carburetor jetting for all kind of conditions. So manufacturers use a jetting chart which gives the idea to the operators to configure the carburetor for specific temperature. You can get the jetting chart with user manual.

8. Low compression

If your dirt bike is not starting then there may be a possible problem it has no or low compression. In such condition kicking, checking spark plugs and battery many times is just a wste of time.No compression or low compression occurs when the top end is worn out or there is a leak on the sealing surface.


To fix the low compression issue in a dirt bike, you need to perform the compression test first. Compression test consists of removing the spark plug, and installing the compression tester in the spark plug hole. you need to fix it tight to get the correct reading.

Now you have to kick your bike multiple times frequently (5-6 times) and get the readings to record. Repeat the process 5 times to get the result with accuracy. After getting the test results you are ready to fix the low compression. If you have a 2 stroke engine then you can solve this issue by replacing the piston or piston rings. Even somtime you need to replace the worn cylinders too.

If you have four stroke dirt bike engine you need to replace the seals, valves.

9. Gas isn’t turned on/no gas in tank

If your dirt bike is not getting gas then definitely it is not going to start whether the gas is not or the fuel tank is empty. For better performance of bike good quality gas is always a good decision. Dirt bike engine works smoothly with non-oxygenatedon gas.

10. Gas is old and varnished

If you are not riding your dike bike regularly then this gas become old and sits in the tank. Its color become dark. After a few months the gas will evaporate and leave a varnish residue inside it. Vrnish is sticky substance. And hence when you start the bike it won’t start.

11. Choke isn’t on/not working properly

Choke is also an important componenet of a dirt bike. When the engine is cold then it is the part which blocks the ait supply to the air-fuel mixture and hence it runs rich and supply more power to start the engine. Once the engine start running choke is turned off as it will cause more fuel consumption.


If choke is not working properly then it can be replaced.

Some more Tips for you when your dirt bike won’t start

When you have fuel injected dirt bike but the engine is not getting fuel: Market also have some fuel injected bikes. They are assumed as difficult to diagnose but they are not so in reality.

It can be diagnosed easily with the help of a cheap DVOM or a basic 12v DC test light by following the steps, I have mentioned below:

The first step of the diagnosis is to ensure that the engine is getting the fuel or not. It is common to make a mistake while doing diagnosis if you have not seen the sprayed fuel around the injector nozzle.

But if don’t have much money to invest do the following– do not put directly any sort of diagnosis on the fuel pressurization system, put some fuel to the engine first through the intake trait.

You can do it by removing the intake trait. Remove the air filter and squirt some fuel into the intake trait by any bottle around you try to start the engine.

There will be two conditions of it when:

  1. It starts
  2. It does not start

Condition No. 1:-

“It starts”

When your dirt Bike start and dies after few seconds by putting some fuel to the fuel injection system. This is the sign that the engine of the dirt bike is in good condition and the spark is generated for running so its ignition system is also in a good state.

Then it is proved that absence of fuel is the cause of not starting. Put fuel to the system and go back to riding again.

Condition No. 2:-

“It does not start”

In case your dirt Bike won’t start after adding some fuel to it, it indicate that the problem is not due to the absence of fuel/gas in it.

It is must that there is some problem in the parts for electrical system of your dirt bike which you can easily fixed by going to any garage present near you or you can also check or find the issue by the help of compression tester.

The bike should be cleaned before beginning of the service if it is a carburetted bike. Right amount of fuel injected and pressure and injector signal are pre requirements of any fuel injected system.

Ensure that your dirt bike is clean only then you can start the diagnosis of the dirt bike.

Detail description about the air filter and the intake trait :–

When the air filter is not in the good condition then you will obviously wants to change it with the new one because of the dirty air filter your dirt bike engine may won’t breathe properly.

Check the new spark plug with a good and cheap compression tester. If the air filter worned or choked the dirty air particles get into the bikes engine and start creating problem low compression in the pump and harm to the other parts of the dirt bike.

Your dirt bike have low compression:- when your dirt bike have low compression then it will surely not start.

Be ready to do a compression test it will give you the idea about the condition of topend whether the topend is worn out or not. Push start the dirt bike if it do have a kick start.


There are many other more reasons like– No spark, poor electrical connections, blown gasket, etc. I have mentioned all the possible condition for not starting of a dirt bike. If these steps for tricks do not resolve your problem then go the factory service as early as you want to ride your dirt bike again.

Sources: https://www.motosport.com, https://www.xtrememotox.com