What causes back fire on a motorcycle?

Answer by  hubb (47)

This can be caused by improper timing, fuel settings too lean or rich, air leak in intake or air leak in exhaust manifold. If timing is OK, then simply squirt some carb cleaner around outside of both intake and exhaust manifold. If the engine revs or starts to dye out, then you have found your problem.

Answer by  Seventy1 (28)

Backfire is either unburnt fuel igniting in the exhaust system or in the intake manifold. Exhaust is more common and it creates a loud bang instead of a poof type noise when backfiring through carbs or a throttle body. A rich fuel mixure or poor/incomplete ignition causes exhaust backfires. Some bikes run rich on decel and will lightly backfire.

Answer by  friend83 (52)

Either the carborator is running too rich or the spark plugs are fouled. Pull out the spark plugs and see if they have carbon build up or are wet. If wet the carborator is running too rich, replace the plugs and adjust the mixture screw on the carborator.

Answer by  Bootsie (36)

Backfires occur when intake valves are not shut prior to fuel combustion. Can occur in intake or exhaust system - with a loud pop, loss of power and/or forward motion.

Answer by  moorthi (37)

One possible cause is a malfunction of the ignition timing and carburetor malfunction, such as jams or misaligned carburetor jets considered in terms of probability,

Answer by  aratliff (111)

Backfire can be caused on a motorcycle if the spark plugs need to be replaced or if it is experiencing a bad air to fuel ratio.