The firing sound from the silencer of a bike is typically referred to as a "backfire." Backfiring can occur due to various reasons, and the specific cause can depend on the type of engine, fuel system, and exhaust setup of the motorcycle. Here are a few common reasons for backfiring:
Fuel-air mixture: Backfiring can happen when an overly rich or lean fuel-air mixture enters the exhaust system. If there is an insufficient amount of air or excessive fuel in the combustion chamber, the unburnt fuel can ignite in the exhaust system, causing the popping or firing sound.
Ignition timing: Incorrect ignition timing can also lead to backfiring. When the spark plug fires at the wrong moment during the engine's combustion cycle, it can result in unburnt fuel reaching the exhaust system and causing backfires.
Exhaust system modifications: Aftermarket modifications to the exhaust system, such as installing a free-flowing exhaust or removing baffles, can alter the back pressure in the system. This change in back pressure can influence the fuel-air mixture, potentially leading to backfiring.
Engine problems: Issues such as a malfunctioning spark plug, faulty ignition coil, or clogged fuel injectors can disrupt the combustion process and contribute to backfiring.
It's important to note that while occasional backfiring may not be a cause for concern, persistent or excessive backfiring could indicate an underlying problem with the motorcycle's engine or fuel system. If you're experiencing frequent or severe backfiring, it is advisable to have your motorcycle inspected by a qualified mechanic to diagnose and resolve the issue.