Motorcycle Lagging When Accelerating? Here’s Why (8 Solutions)

Combustion engines are made functional by the dynamic relationship of the air intake, fuel, and ignition systems which power the pistons to generate the force that spins the rear wheel.

A slight interference with either of these systems can cause a negative impact on a motorcycle’s performance.

This article has dived into the specific failures within each of those critical systems and how to stop these failures to prevent your bike from lagging when accelerating.

Here are ways to prevent your motorcycle from lagging when accelerating:

1. Re-Tune Your Ignition Timing

The ignition timing on modern motorcycles is sustained by the bike’s Electronic Control Unit or ECU.

Like any computer, the ECU needs to be flashed, defragmented, and updated periodically to maintain communication with the various engine sensor monitors.

The ignition timing of some motorcycles, such as vintage bikes, has been related with a mechanical system of breaker points synchronized to charge and fire the ignition coil at the most needed time to power the piston into its next cycle.

As the breaker point contacts wear down, their timing slowly changes until it delays or advances enough to cause the motorcycle to lag while hitting the throttle.

If the ignition timing of your motorcycle is delayed, your fuel won’t ignite until the piston completes its cycle. If, on the other hand, your ignition timing is advanced, your engine’s performance will dip. 

You’ll then hear loud engine knocking sounds from the fuel as it ignites at the wrong time while hindering the piston’s rotation.

Not only will delayed ignition timing cause a noticeable dip in your motorcycle’s fuel efficiency, it can also cause the bike to lag under acceleration.

It is important to note the following:

  • If an ECU-regulated motorcycle is undergoing ignition timing issues, the ECU either needs to be updated, flashed, or replaced.
  • Worn ignition breaker points must be replaced and re-tuned to correct the ignition timing on a vintage bike. Else, it will continue to lose power while revving.

2. Inspect and Change Your Spark Plugs

Another common cause of a motorcycle lagging while accelerating is a faulty or damaged ignition system component. This is most commonly the spark plug and the ignition coil.

Always inspect the spark plugs of your motorcycle based on the owner’s manual’s suggested service intervals, especially when the bike lags while throttling. We also suggest you examine the spark plug-ignition coil connector. 

If that didn’t suffice, inspect the ignition leads and the coil for any signs of corrosion, wear, or overheating.

Note the following about the spark plugs of your motorcycle:

  • As its name implies, the spark plug starts the entire ignition process.
  • All spark plugs becomes weak eventually from the stress of their general functioning.
  • Once the plug wears out, the components of the ignition system will become weakened. 

A debilitated ignition system is a common cause of power loss, lagging, and even stalling on your motorcycle while accelerating. This is because a faulty ignition system can’t provide the power needed to combust the fuel mix. 

Make sure to also check our article on why a motorcycle won’t start after running out of gas.

3. Restore Your Engine’s Internal Compression

If your motorcycle’s internal compression rating is compromised by improper seals, faulty gaskets, or incorrect bores, the piston’s momentum will take a negative impact. This will, in turn, cause your motorcycle to lag when acceleration. 

Note that cylinder seals maintain the compression inside combustion engines. If the seal between the cylinder bore and the piston rings is damaged or a gasket is seated incorrectly, the compression in the engine can escape through the break in the engine’s seal.

That is, when you accelerate your motorcycle, the attempted increase in throttle only pushes the internal compression out through the gap. This will cause the motorcycle’s performance and revving power to fade instantly. 

To correct this, you need to locate the broken seal or gasket, which often demands uninstalling and opening your bike’s engine case.

If the compression is decreased due to the cylinder bore being compromised, worn, corrupted, or damaged, the cylinder may need to be re-bored to seal the reduction.

Another possible fix is to install bigger pistons and piston rings to seal the cylinder gap.

Suppose you’re inexperienced with engine modifications like this, we suggest you have a pro mechanic dismount and examine your bike’s engine for compression leaks. Besides, this issue can be challenging to diagnose and hyper-technical to repair. 

4. Free Up Your Air Intake

If a clogged air filter or an air leak in an intake manifold hinders your motorcycle’s airflow, you’ll notice a weakened throttle response when you accelerate.

It is important to consider the following notes:

  • The air inrush is significantly reduced if the air filter is clogged with grime and dirt.

  • Once the air intake is obstructed, the combustion chamber consumes more fuel.

  • If your bike’s throttle lag is accompanied by a significant dip in fuel efficiency, a clogged air intake filter may be the reason.

  • Also, a tear in your air filter can be just as detrimental, as it allows dirt to enter your intake manifolds and block the airflow on its route to the combustion chamber.

  • Finally, a crack in a manifold or a damaged seal can allow air to escape. Besides, any compromise to your combustion chamber’s air supply can cause your motorcycle to lag while accelerating. 

Some bikes come equipped with reusable air filters you can clean with warm water or degreaser, depending on the type and design of the filter.

Adversely, you’ll want to change out the disposable paper filters during the routine service interval outlined in your bike’s manual.

If you suspect a clogged air intake filter to be the cause of your motorcycle lagging when you use the throttle, to the point that it sometimes stalls, blowing out the filter is just a temporary fix.

Please, also read our post on the 11 motorcycle patches to avoid.

5. Unclog Your Fuel Filter

Unclogging the fuel filter of your bike would also prevent it from lagging when accelerating the throttle. Moisture, tank rust or mineral buildup, carbon deposits, and coagulated fuel can all jam the filter and hinder fuel flow.

Once the fuel filter is clogged, it prevents the fuel from entering the combustion chamber. Instead, it ignites when you hit the throttle. This is the point when you’ll see air gurgling in the fuel tank, and you’ll feel the acceleration dragging.

If the fuel filter is clogged severely enough, the motorcycle may stall when you try to spike RPMs. 

Some motorcycles have fuel filters on the outside, which are easy to inspect and service. Many other bikes keep their fuel filters in the tank submerged in gasoline.

Therefore, to service an internal fuel tank filter, you or your mechanic must remove the whole fuel tank, drain the fuel, and likely disconnect the fuel lines.

6. Drain Your Contaminated Fuel

Failure to fill up your motorcycle’s fuel tank with gasoline before a lengthy storage period allows air to permeate your fuel supply. The fact is, air carries moisture into your fuel lines. So, when next you ride, the water content hinders ignition, causing your throttle to lag. 

If you think your motorcycle lags while accelerating because of moisture in your fuel, empty the tank of all fuel. Follow the steps below to do that.

  • Uninstall the fuel tank and drain the fuel lines.
  • Blow through the fuel lines, drying them out entirely.
  • Re-attach the fuel tank and lines.
  • Fill the tank with fresh, high-quality fuel.
  • Test ride your motorcycle to ensure it isn’t lagging when accelerating.

7. Unclog Your Carburetor or Fuel Injectors

All motorcycles have some contraption to inject air and fuel into the combustion chamber. While vintage bikes used carburetors to mix and maintain the air (fuel ratio and flow), modern motos work with ECU-regulated fuel injectors.

If your motorcycle works with fuel injectors, you must diagnose your ECU and inspect its tuning. You should also inspect the carburetor or throttle. Ensure it’s cleaned, balanced, and maintained regarding the suggested service intervals.

Failure to keep up with routine maintenance can cause clogs in the carburetor. Another effect is that your injectors can go out of sync, and the motorcycle will lag when accelerating. 

8. Take Your Bike Out of Limp Mode

The engine operations of modern motorcycles are regulated by complex engine management systems controlled by an Electronic Computer Unit or ECU.

The ECU communicates with a network of sensors to monitor its electronics and adjust air and fuel flow according to its dynamic processes.

In addition to optimizing the operation of your engine, the ECU also provides safety features that prevent engine damage, overheating, and unsolicited mishaps that can result in loss of control.

If your motorcycle’s ECU detects an abnormality in your fuel system, it will move the engine into a “limp mode.”

The limp mode causes a significant reduction in power, performance, and acceleration to prevent overheating or engine damage in the event of a fuel system failure.

    Also check the reasons motorcycles can shut off while on motion.

Sometimes, a fuel system sensor becomes defective and fails to communicate with the bike’s ECU. Some ECUs may, in turn, assume the loss of communication is caused by a fuel system failure and enter limp mode automatically when there’s a lapse in the sensor signal.

Whether it’s a fuel system failure or a faulty sensor reading, if your motorcycle’s ECU enters limp mode, your bike might lag during acceleration, die completely, or not start at all. 


Why is my motorcycle bogging on acceleration? | Westendmotorsports

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