Why does a motorcycle's exhaust pipe keep backfiring?
2 Answers
Motorcycle exhaust pipe "backfiring" is caused by secondary combustion of gasoline. The specific reasons for gasoline secondary combustion are as follows: 1. Unreasonable air-fuel mixture ratio: If the air-fuel mixture is too rich or too lean, it may cause incomplete combustion of gasoline in the cylinder, leading to re-ignition and continued combustion in the exhaust pipe, resulting in backfiring. 2. Ignition system issues: If backfiring occurs during acceleration, it is often due to ignition system problems. A four-stroke internal combustion engine theoretically needs to ignite once every two revolutions. 3. Excessive impurities in gasoline: Poor fuel quality, such as excessive water or other impurities, can cause incomplete combustion. 4. Weather conditions: In winter, it may be difficult to start the engine, requiring multiple attempts, during which a lot of gasoline may have already spread into the exhaust pipe. This can lead to accumulated fuel in the exhaust pipe, causing backfiring.
I've encountered the issue of motorcycle exhaust backfiring several times. Simply put, it's when unburned gasoline explodes in the exhaust pipe. Common causes include incorrect air-fuel mixture ratio (too much fuel or too little air), where unburned mixture escapes into the exhaust and ignites when heated. Another reason is improper ignition timing - if the spark plug fires too early or too late, combustion fails to occur properly. Severe carbon buildup on spark plugs or leaking high-voltage wires can weaken ignition. Poor valve sealing leading to compression loss is another frequent cause. Exhaust pipe cracks or leaks can exacerbate this phenomenon. Sometimes using low-quality fuel may also cause abnormal combustion. This problem shouldn't be ignored - prolonged occurrence may damage the catalytic converter or even affect the engine.
