Dirt Bike Won’t Start: 11 Possible Reasons (Explained)

Do you have trouble getting your bike to start despite your best efforts? It can be really annoying. You must not miss these 11 issues with the fixes if you don’t want to get into difficulty again.

The dirt bike won’t start if the gas is old and vernished, the gas is not turned on, the choke is off, the carburetor is dirty, the bike has low compression, there is a leak in the intake air, the kill switch is broken, there is a spark problem, the battery is dead, the carburetor jetting is improperly adjusted, or the air filter is dirty.

It might be really problematic when you want to enjoy a relaxing ride and find that your dirt bike is dead or eventually won’t start. It is advisable to check a list of possible causes of dirt bike starting problems. If you want to learn how to diagnose your dirt bike, you’ve come to the perfect place.

In this article, we’ll go through the fundamentals of why a dirt bike won’t start and what to do in such situation. to allow you to restart your dirt bike! If your dirt bike has been sitting in your garage or storage for more than two years without being started.

procedure for beginning:

Any dirt bike can be started with merely a spark in the engine and the right proportion of air and fuel during the combustion process. The spark won’t be produced if the mixture doesn’t burn.

To identify the root of the problem, you must take care of every component of your dirt bike. To identify the problem, the proper actions should be conducted. Try to find a solution as soon as you can. To investigate the problem, start the engine of your vehicle. Make sure the gas is not varnished or outdated.

If the carburetor has any of the following issues: a filthy air filter, low compression, an intake air leak, a broken switch, a fouled spark plug, a dirty fuel injector, or a clogged fuel injector, clean it. Let’s take a closer look at them:

11 Most Common Reasons Why your dirt bike won’t start?

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

  1. No spark
  2. Battery is too weak
  3. Carburetor is dirty
  4. Air filter is dirty
  5. Fuel injector is clogged or dirty
  6. Intake air leak
  7. Badly tuned carburetor jetting
  8. Low compression
  9. Gas isn’t turned on/no gas in tank
  10. Gas is old and varnished
  11. Choke isn’t on/not working properly

1. No spark

If everything is fine but your bike still won’t start, there may not be enough spark. Here is how to investigate this problem.

Taking off the spark plug is the first step. Connect to its cap, then allow it to rest at the engine. Before kicking the lever, switch off the lights and ride your bike to a dark area. A tiny blue spark that is produced during the kick can be seen. However, if there is no spark, the bike will undoubtedly not start.


Reinstall the spark plug in the ignition coil after removing it from the cylinder block, and then start the dirt bike to check for spark. A motocross bike with no spark can be fixed using this.

If there is no spark, change the spark plug, but first examine all other electrical parts.

2. Battery is too weak

A battery powers the starter on a dirt bike that is designed to run on electricity. Low-charge batteries cannot generate enough power to start the engine.

Fix: There are two ways to fix a low power battery that is the cause of your bike not starting. Try charging it first, and if that doesn’t help, you’ll need to swap out the old battery for a new one. If you don’t ride your dirt bike frequently, battery damage can be the problem. It lasts a long time and consistently produces wonderful results.

The best friends of dirt bike racers are compressed air and carb cleaner. Lose the clamp, spin the carburetor, and spray the jets with cleaning solution. By taking out the float bowl on the carburetor’s bottom, this method won’t take long and may be finished in a few minutes.

If this hasn’t made a difference, you should get a comprehensive cleaning. Disassemble the motocross bike’s carburetor by entirely removing it. Make careful to thoroughly clean it, paying attention to every crevice.

3. Carburetor is dirty

When a dirt bike doesn’t start properly, the unclean carburetor may be the blame. There are a few ways to determine whether your carb is unclean. Because of the leftover gas, the carburetor, jet, and passageways can frequently become dusty. Even though you can see through it, there is a small amount of debris on it that prevents correct gas flow and causes the engine to not start.


Use high-quality fuel for your dirt bike so that it will operate more smoothly, won’t break down frequently, and will be helpful to you in the long run. When buying gas, always look for high-quality products. Gas for bikes that doesn’t contain oxygen or ethanol works quite well.

4. Air filter is dirty

You should examine the air filter. How soiled is it? Only one of the layers of dirt, mud, or sand can be problematic for the bike. That prevents the bike from moving. Try starting the bike after cleaning the air filter.

You must take care of the air filter propelry if you want to keep your engine in good shape. Your engine works harder and cools off more slowly if your air filter is dirty. It’s crucial to let clean air into your engine, which uses fuel and air to produce power.


Only when it is dirty is a thorough cleaning of the air filter necessary. It is advisable to regularly ride a dirt bike on muddy trails and sand dunes, so clean it up after each long ride. Remove the air filter and use a cleaner to clean it. To cease forcing dirt into the filter fibre, rinse the inside of the device using a garden hose or faucet. Next, dry it with air, and make sure it is totally dry before putting oil on it.

5. Fuel injector is clogged or dirty

If the air-to-fuel ratio in your dirt bike engine is off, it won’t be able to generate enough power to move your dirt bike. Numerous instances of clogged or dirty injectors result in no start. The fuel injector won’t effectively inject the fuel if it’s clogged with debris.


A rigorous cleaning is required to unclog a blocked fuel injector and restore it to better working order. For this job, you want to speak with a qualified mechanic. You cannot clean this by yourself. Of course you can clean them, but I still think a certified mechanic is needed for clogged gasoline injectors. However, if you are well known in this regard, you can handle it yourself.

6. Intake air leak

A motocross bike will be hard to start if there is an air leak in the system. It is necessary to check for cracks in the system, which consists of the nut, nuts, and gasket put between the carburetor, airbox, and engine.

The gasoline and oxygen are diluted as a result of this air leak. The hardest part is identifying the air leak, which is a complex process.


It is simpler to replace the intake boot if you can find the cracked one. A new intake boot costs less money.

7. Badly tuned carburetor jetting

For an engine to perform at its best, tuning is essential because dirt bike carburetors depend heavily on jetting. Air density is influenced by the atmosphere and is constantly shifting.

Performance is impacted by temperature changes, hence engine carburetor jetting is calibrated to maintain balance under these circumstances.

When the temperature rises, the air density falls, and when the temperature falls, the air density rises. Similar to how air density reduces when air pressure rises, and vice versa, as an engine’s operating altitude rises.

You may realise that because the planet is so big and the weather is constantly changing, it is hard to configure a carburetor jet for every circumstance.

Therefore, manufacturers employ a jetting chart that provides operators with guidance on how to set the carburetor at a particular temperature. The jetting chart and user instructions are available.

8. Low compression

If your dirt bike won’t start, there could be an issue with low or no compression. Secondly, repeatedly checking the battery and the spark plugs would be a waste of time in this situation. When the top end is worn out or there is a leak on the sealing surface, there is no compression or low compression.


You must first run a compression test to determine the cause of the dirt bike’s poor compression. To do a compression test, remove the spark plug and insert the compression tester into the spark plug hole. To obtain the proper reading, you must tighten it up.

To get the readings to record, you must now kick your bike repeatedly (5–6 times). To acquire a precise result, carry out the procedure five times. When you receive the test results, you are prepared to address the low compression. Replace the piston or piston rings if your engine is a two-stroke model to address this problem. Sometimes you also need to replace the worn out cylinders.

Replace the seals and valves on your four-stroke dirt bike engine.

9. Gas isn’t turned on/no gas in tank

Regardless of whether the gas tank is full or not, if your dirt bike isn’t getting gas, it won’t start. A sensible idea is always to use high-quality gas for your bike. Non-oxygenated gas provides smooth operation for dirt bike engines.

10. Gas is old and varnished

This gas ages and sits in the tank if your dike bike is not routinely used. It turned a dark colour. A varnish residue will remain inside it after a few months after the gas evaporates. Vrnish is an adhesive material. As a result, the bike won’t start when you turn it on.

11. Choke isn’t on/not working properly

Another crucial component of a dirt bike is the choke. When the engine is cold, this component prevents air from getting to the air-fuel combination, causing it to run rich and require more power to start. The choke is turned off after the engine is going since it increases fuel consumption.


A choke can be replaced if it is malfunctioning.

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

If your fuel-injected dirt bike’s engine isn’t receiving fuel, there are fuel-injected bikes available on the market. They are not as challenging to diagnose as is commonly believed.

By using an inexpensive DVOM or a simple 12v DC test light and following the methods I’ve listed below, it can be quickly diagnosed:

Verifying if the engine is receiving fuel or not is the first step in the diagnosis process. If you don’t see the gasoline spraying from the injector nozzle, it’s usual to diagnose incorrectly.

However, if you don’t have much money to spend, you should follow these instructions instead of diagnosing the fuel pressurisation system directly. Instead, fuel the engine through the intake first.

To accomplish this, get rid of the intake attribute. Remove the air filter before trying to start the engine by spraying some petrol into the intake manifold from any nearby bottle.

There will be two prerequisites for it:

  1. It starts
  2. It does not start

Condition No. 1:-

“It starts”

By adding fuel to the fuel injection system when your dirt bike starts and then stops after a short period of time. This is a sign that the dirt bike’s engine is in good shape and that the ignition system is also in good shape because a spark is produced when the bike is going.

The lack of fuel is then shown to be the root of the vehicle’s inability to start. Refuel your vehicle and start riding again.

Condition No. 2:-

“It does not start”

If your dirt bike still won’t start after you add fuel to it, it means the issue isn’t with the fuel or gas in it.

There must be a problem with the components of your dirt bike’s electrical system, which you can simply remedy by visiting any nearby garage or by using a compression tester to examine or identify the problem.

If it is a carburetted bike, the bike needs to be cleaned before the servicing can begin. Any fuel-injection system must have the proper pressure, injector signal, and fuel amount injected.

Only once you have made sure that your dirt bike is clean should you begin the diagnosis process.

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

If the air filter is not in excellent shape, you should replace it right away because a dirty air filter could prevent your dirt bike engine from breathing correctly.

Utilize a reliable and affordable compression tester to examine the new spark plug. If the dirt bike’s air filter is worn out or blocked, unclean air particles enter the engine and start causing issues with low compression in the pump and damage to the other components.

Your dirt bike’s compression is too low: A dirt bike with inadequate compression won’t start.

Prepare to perform a compression test; it will enable you to determine whether or not the topend is in good condition. If the dirt bike has a kick start, push start it.


There are numerous additional causes, including blown gaskets, bad electrical connections, and no spark. All the potential reasons why a dirt bike might not start have been covered. If following these trick-related methods does not solve your issue, take your dirt bike to the factory for repair as soon as you wish to ride it again.

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