What Causes a Motorcycle to Backfire?

A backfire describes the loud pop or bang you hear in your motorcycle’s exhaust when it’s not tuned quite right.

There are a number of different reasons why your motorcycle backfires, some easier to fix than others.

Backfire is caused by a secondary, unexpected combustion when there is unburnt fuel in the exhaust.

The underlying cause of motorcycle backfires is an improper fuel mixture.

Reasons for Motorcycle Backfire

The improper fuel mixture that causes the backfire can be attributed to a number of things. The most common ones to check are:

  • Loose exhaust pipes or carb manifolds.
  • Improper exhaust system for the current jetting.
  • Weak spark.
  • Improper ignition timing.
  • Too much fuel.
  • Too much air.
  • Dirty carbs or clogged jets.

Fixing a Motorcycle Backfire

Start with the easy fixes first and move down the list:

Backfire can be prevented and a properly tuned engine can be maintained with regular maintenance and inspection.


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