Why does a motorcycle's exhaust backfire?

[LondynRose]

Motorcycle exhaust backfiring is fundamentally caused by combustible gases entering the exhaust pipe and reigniting upon encountering high temperatures or sparks. Main reasons: 1. The air-fuel mixture is too rich or too lean. The choke is not open, or the air filter is clogged. 2. The spark plug has weak or intermittent ignition. Any issue with electrical components in the ignition circuit may cause ignition failure. 3. Faults such as valve leakage result in incomplete combustion or insufficient cylinder pressure. 4. Incorrect ignition timing or valve timing. 5. Excessive speed and high temperatures may also cause temporary backfiring due to sudden enrichment of the air-fuel mixture. 6. Poor fuel quality leads to incomplete combustion and backfiring. 7. Unstable mixture supply.