12 Reasons Why Your Yamaha Dirt Bike Won’t Start & How To Fix

A common nightmare for dirt bikers is that their bike is not starting. This issue is something that bikers often face, especially those who love to spend their time off-roading.

One of the most reliable dirt bike brands, off-roading dirt bikes from Yamaha is also not free from this common issue.

However, maintaining a dirt bike is relatively easier than other bikes. Fuel, air, spark, and compressor are the key components for running a dirt bike anywhere in the world.

Ensuring these components are working properly, a rider can easily fix his/her off-road bikes even by themselves.

People often Google why a brand like Yamaha also encounters this kind of problem and how to fix it.

So, here are mainly 12 Reasons, Why Your Yamaha Dirt Bike Won’t Start & How To Fix It:

Why Your Yamaha Dirt Bike Won’t Start & How To Fix

Yamaha Dirt Bike Won’t Start & How To Fix

1. Check The Spark

A common reason for your bike not getting started is that the engine is not getting a proper spark from the plug. A spark plug is a necessary component to ignite fuel combustion.

If your bike is not making the engine sound after trying to kick start or electrical start, the plug might have a problem.

To solve this issue, follow the following process:

  • Remove the spark plug from the cylinder block first.
  • Then reconnect it with the cap.
  • Now put the spark plug close to the metal part of the bike and try to start the engine by kick-starting. You can try electrically if your bike has the option for it.
  • While doing that, if a blue-colored spark comes from the plug, then the plug itself is okay. But if no spark comes out, it’s time to change the plug.
  • After changing the spark, check all the electric parts to be sure.

2. Check If The Battery Is Working Properly

Motocross or dirt bike with an electric starter is equipped with a battery to make it start. If the bike is not used often, there is a high chance that the battery will become weak. Due to its poor condition, it cannot supply enough power to the starter motor.

In two ways, a problem related to the battery can be handled:

  • Try to recharge the battery if it’s not a dry-cell one. If it works, then repeat the process whenever you face it.
  • If the battery is too weak to supply power even after charging, then it’s time to replace the battery. Please do not forget to recycle the older ones properly.

3. Monitor The Condition Of The Air Filter

The air filter is a crucial component to running your bike smoothly. As your off-road dirt bike frequently hits mud, dirt, cobbles, and sand, there is a high chance that your air filter quickly becomes dirty.

If dirt, mud, or sand forms a layer over the air filter, it blocks the necessary air for combustion.

A healthy engine requires a clean air filter to cool down properly. Your bike will not start correctly if air cannot pass through the filter.

  • Check the air filter frequently. If you use a washable filter, wash it with a garden hose or a simple faucet.
  • Rinse the filter softly from the inside to prevent the dirt from being pushed to the filter’s fiber. If the filter’s health is fragile, it would be wise to change it and install a new one.

4. Check Your Carb If It Works

Carburetors are very common in the dirt bike segment as most riders love carbs for its simplicity.

Due to the diverse riding style, many dirt bikers now come with an electrical fuel injection system to perform better at high-altitude riding.

However, a dirty carburetor can prevent you from starting your bike. Usually, old fuel or dirt can clog the passageway and jets. For that reason, the bike won’t start.

Carburetor cleaner and compressed air can help riders to clean their faulty carburetors easily.

Follow these steps to know the further process:

  • Ensure the engine is cold to work on.
  • Then lose the carburetor clamps, and check the overflow carefully. If liquid spills out, the carburetor itself is not an issue.
  • Then check the fuel line and clean it to make a perfect fuel supply in the carburetor. If the fuel supply is still not working, carefully remove the carburetor and disassemble it.
  • Make sure to clean it thoroughly.
  • Remove dirt and old gas from every corner. Even if it looks clean enough, make sure to clean it again, as often dirt mixed with fuel can clog the passageway.
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5. Check If The Fuel Injection (Fi) System Is Working Or Not

Nowadays, many riders are leaning towards dirt bikes with an electrical fuel injection system to get the best fuel mapping in any terrain.

The FI system performs well on high-mountain terrain where sudden elevation needs a diverse range of air-fuel mixture.

However, a clogged fuel injector will like to ensure that your Yamaha dirt bike won’t start.

Cleaning a fuel injector requires advanced tools and modules and adequate knowledge about the system. A qualified mechanic is recommended to clean, maintain and tune the fuel injector and make it run smoothly.

Of course, you can clean it yourself in adverse conditions. Nonetheless, contact your local Yamaha Service Point to make sure the fuel injector is cleaned properly.

6. Perhaps The Compression Of Your Bike Is Low

Compression plays a major role in making your engine start. If the pistons and the piston rings wear out, you will find it difficult to start your engine.

Even if you manage to make it start, a lack of energy output will surely make you uncomfortable to ride. In this event, a completely new spark plug or battery will not help you to start your bike.

To solve this issue, a compression test is needed to determine how low the compression is.

To conduct a compression test:

  • Remove the spark plug, insert the compression tester in the plug hole and tightly fix it to get an accurate reading.
  • Now kick your bike 5-6 times to get a reading in the tester. Do that several times to get a proper reading. You can solve the problem after the test.
  • Change the seals or valves which are worn out.

However, in two-stroke bikes, you need to change your piston or piston ring, which is dilapidated. Sometimes, the whole cylinder needs to be replaced.

7. Fill Up Your Gas Tank/ Turn On The Gas Switch

Maybe your bike is not facing any major maintenance issues. Perhaps it’s less complicated. Check your tank if it’s empty or not. If your bike remains in the garage for a long time, there is a high chance you emptied the tank. Fill it in and try to start it.

If your tank has gas in it already, try to check if the gas switch is on. If not, flip it, and you are ready to dominate tracks.

8. Your Bike Is Facing An Intake Air Leak

Your engine will probably not start if there is a leak in your air intake system. You may think about how it works. The air intake system mixes air with fuel to make perfect combustion.

You need to check this whole air intake system, including the nut joint area and gaskets, to find cracks where the air is getting sucked in and diluting the fuel-air mixture.

Though it sounds simple, these specific problems require much time to solve, as finding cracks in your system is not easy. Whenever this happens, replacing the system is better than fixing it.

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9. Gas May Be An Issue

The gas inside your tank becomes less efficient when you store your dirt bike for a long time. As it becomes old, the color gradually changes and becomes dark.

After a few months, the gas eventually evaporates and leaves a sticky residue in the tank. If that’s the case, your engine will not start due to fuel shortage.

How to solve it? Just clean your tank if there is a sticky residue inside of it, fill it with new gas and let it rip the track.

10. Check the Chokes

Choke is an important component for dirt bikes. It blocks the air supply to the air-fuel mixture when the engine is cold.

You can turn on the choke when starting your engine so that it can supply more power to the engine.

However, turning off the choke after starting your engine will lead to more fuel consumption.

Check if your choke is working properly or not. An engine will be less likely to start if the choke is not working properly.

11. Carburetor Jet Is Not Tuned Properly

Jetting is a crucial part of a carburetor as its tune determines how perfectly your engine will operate. You need to understand how it works.

Usually, the density of air changes depending on the atmosphere. Air density decreases when the temperature increases and the reverse happens when the temperature falls.

The carburetor in your bike is designed so that the jetting system can work, balancing the air condition.

However, it is not possible to set up a carburetor to jet properly in every condition. For that reason, a default jet chart configures the carburetor to work at a specific temperature or altitude.

If you understand the principle, you can fine-tune your carburetor jetting to start your bike effortlessly.

12. Ignition System Is Not Working

A bike stator is a component that creates voltage for the plug and charges the battery. A failing stator will cause a poor spark, and your engine will likely not start. In addition, several factors may cause a fault in the ignition system.

Gaps in the spark plug, bad plug cap, faulty coil, failing stator, damaged CDI, or ECU may cause an electric malfunction for which your bike won’t start.

If that’s the case, it’s time to check your electrical system. Use an inline spark tester to check all the electric components of your bike.

Yamaha Dirt Bike Won’t Start

Yamaha Dirt Bike Won’t Start – FAQ


Multiple reasons can cause a problem leading to your bike not getting started. As off-road bikes are used in relatively more rough ways than normal bikes, it is not an uncommon issue for riders to face hassles as such.

However, if you see your Yamaha dirt bike won’t start, follow the steps and check thoroughly to find the root cause.

As these bikes are built in a way that can be fixed without major hassles most of the time, a set of simple and quick steps will solve basic issues when you are on a trail, exploring nature with your off-road beast.

If the problem still remains unsolved, contact your nearest service centre for assistance and conduct a factory service if possible.

5/5 - (2 votes)

I’ve been riding (bicycles) my entire life and am passionate about everything that comes along with it. I wouldn’t call myself a true “roadie”. I’m just a guy that loves riding because of the pure joy it brings.

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