Motorcycle Losing Power When Accelerating: 8 Possible Causes

When you accelerate your motorcycle and it loses power, you’ll be surprised. It is a frustrating situation, but don’t worry; I can help you resolve it. Since I identified potential causes for this problem, I have already fixed it.

You must not skip these 8 causes that I have listed here if you are now experiencing this problem.

Accelerating issues can also be annoying and, in the wrong circumstances, even deadly. But once one is aware of what to do, everything is simpler.

The issue could be brought on by faults with the fuel delivery system, carburetors, worn-out or unclean spark plugs, etc. Fortunately, the majority of these issues may be fixed without a trip to the technician.

You should be able to fix the problem by simply cleaning or replacing your spark plugs, air filter, or carburetor.

We shall discuss the reasons of this problem and solutions in this article.

Why Is My Motorcycle Losing Power When Accelerating?

1. Fuel Delivery problem

When a motorcycle’s fuel delivery is not working correctly, it can cause several problems. Your motorcycle will begin to lose power while accelerating if it isn’t getting sufficient fuel.

Fuel delivery problems can come from several things, such as a faulty fuel pump, a clogged fuel filter, or leaky fuel injectors.

If you suspect that your fuel delivery system is the issue, then it’s best to take it to a mechanic for further diagnosis.

2. Carburetor Problem

Another potential cause of power loss is carburetor problems. If your carburetor is dirty or out of adjustment, the carburetor spring may be turned backward.

It can prevent the engine from getting the correct mixture of air and fuel. This will result in a loss of power and decreased performance.

This is a problem that is usually caused by someone rebuilding the carburetor themselves.

If you or someone else has recently rebuilt the carburetor and noticed that you’re having acceleration problems, the likely culprit could be a backward carburetor spring or a dirty carburetor.

3. Extra Slack In The Throttle Cable

There is a cable connected to the throttle, the cable is known as the throttle cable, and runs down to connect to the carburetor.

This cable tells the carburetor how wide the butterfly valve needs to open and when it needs to close, depending on how fast or slow you want to go.

You may have excess slack on the throttle cable where it is connected to the carburetor. This in turn will lessen its ability to open the butterfly valve because it’s not giving it a full pull.

You will have an uneven air and fuel mix which will cause your motorcycle to lose power when accelerating.

4. Exhaust System Restrictions

When a motorcycle’s exhaust system is restricted, it can cause reduced power, poor acceleration, a loss of top speed, increased fuel consumption, and excessive heat in the engine and exhaust system.

When your exhaust system is restricted, it can also cause power loss while accelerating.

This is because the exhaust gases can’t flow freely, and as a result, they build up in the cylinders and prevent the engine from breathing properly.

5. Vacuum Leak

This can be caused by either faulty gaskets on the carburetor or cracked or lose intake boots.

While a carburetor is trying to make the right air and fuel mixture to deliver to the engine, it happens inside the carburetor which should be sealed without disturbance for it to work right.

If air sneaks in from the faulty gaskets or the intake boots, it can disrupt the proper mixture it’s trying to make. This is referred to as a vacuum leak.

A vacuum leak leads to too much air being added to the air-fuel mixture the carburetor makes.

When your motorcycle engine is getting too much air and not enough fuel, it won’t run right. The more gas you try to give the motorcycle, the more air will be sucked into the unwanted holes which will ultimately make you lose power.

6. Clogged air filter

Another potential cause of power loss is a clogged air filter. If your air filter is dirty, it can restrict airflow to the engine and prevent it from getting the oxygen it needs to combust properly.

This will result in a loss of power, as well as decreased fuel economy and acceleration.

7. Dirty or Old Spark Plugs

One potential cause of power loss is dirty or old spark plugs. Over time, spark plugs can become fouled with oil, debris, and carbon deposits.

This can prevent them from firing properly, and as a result, your engine won’t be able to produce as much power.

8. Bad Timing Advance

The timing advance on a motorcycle is the mechanism that controls when the spark plugs ignite the fuel/air mixture in the engine.

It is important to adjust the timing advance correctly so that the engine runs smoothly and efficiently.

Another potential cause of power loss is bad timing advance. This refers to the timing of the spark plug’s firing about the piston position.

If the timing is too far advanced, it can cause “knocking” or “pinging” sounds, as well as decreased performance and fuel economy.

How To Fix Power Loss When Accelerating?

1. Fix a faulty motorcycle’s fuel delivery system

It is necessary to take the entire system off the bike in order to clean or replace any of the components that are not functioning properly.

Because this is something that can be tough to do, it is recommended to take it to a professional mechanic to have it done.

2. Fix the carburetor problem

It will be necessary for you to unhook the carburetor spring that is connected to the throttle cable and then reattach it in the opposite direction.

You should be able to witness an improvement in performance by simply cleaning or adjusting your carburetor. This is a relatively small issue that can be remedied without much difficulty.

3. Fix the throttle cable slackness:

There is typically a nut that can be tightened a few inches above the knob that connects to the carburetor at the end of the throttle wire. You might make an effort to tighten that up so that there is no extra room for movement.

When you ride an older motorcycle, the throttle cable may experience a slight amount of stretching at various points.

This is not something that can be fixed by pulling things in closer. It will not be difficult to fix; all that will be required is a new throttle cable.

Depending on the make and model of your motorbike, the removal of the carburetor may not even be necessary in order to replace the throttle cables. This is because replacing the throttle cables is a rather straightforward process.

4. Clean or replace a motorcycle’s exhaust system

It is anticipated that you will take the complete system off of the bike.

Because this is something that can be tough to do, it is recommended to take it to a professional mechanic to have it done.

5. Fix the vacuum leak

Check out the intake boots that are attached to your carburetor. After some amount of time, it is not uncommon for them to shatter or become brittle.

Check that the quick-release hose clamps that are located around the intake boots are secure and not allowing any air to pass through them. Alternately, new intake boots should be placed if necessary.

In addition to this, you will need to inspect the gaskets that are attached to the carburetor. These are situated in the area of the carburetor that connects the float bowl to the remainder of the device.

In addition to this, they frequently grow brittle and shatter. After evaluating them, you should replace them if necessary in order to guarantee a good seal between the components.

If there is a vacuum port running from the top of the engine to the carburetor, you should replace the vacuum hose so that it functions exactly as it did when it came out of the factory.

You can close off the vacuum port if it was for a system that you are no longer using because you do not require it.

6. Clean A Clogged Air Filter?

  • Remove the air filter from the bike.
  • Use a compressed air gun to blast the dirt and debris out of the filter.
  • Rinse the filter with warm water until all of the dirt and debris is gone.
  • Allow the filter to dry completely before reassembling it on the bike.
  • Reinstall the air filter on the bike and start it up to test it.

7. Clean Spark Plugs?

Fixing a problem caused by unclean spark plugs is a simple matter to attend to.

A noticeable improvement can be attained by either cleaning or changing the spark plugs in your vehicle.

  • Remove the spark plugs from the bike.
  • Use a wire brush to scrub the dirt and debris off of the plugs.
  • Rinse the plugs with gasoline until all of the dirt and debris is gone.
  • Allow the plugs to dry completely before reassembling them on the bike.
  • Reinstall the spark plugs on the bike and start it up to test it.

8. Adjust Timing Advance

It is not a difficulty to repair a poor timing advance; all that needs to be done is adjust the timing, and you should observe an improvement in performance.


When it comes to accelerating, there are many different factors that could contribute to a loss of power. Clogged air filters, problems with fuel delivery, spark plugs that are dirty or old, problems with the carburetor, exhaust system constraints, and improper timing advancements are some of the most prevalent causes of this issue.

If you are having any of these issues, you should be able to identify and resolve the issue on your own by following the steps outlined in this post. If you are having any of these issues, you can find this article here.

And if the issue continues to exist, the best course of action is to take the vehicle to a mechanic so that the problem may be properly diagnosed.

Many thanks for taking the time to read this.