The muffler reduces exhaust noise and conducts the exhaust gases back away from the rider while keeping power loss to a minimum. If much carbon is built up inside the muffler, exhaust efficiency is reduced, which lowers the engine output power.
To remove built up carbon, first remove the muffler, and then take off the tailpiece. Dangle a chain in the muffler and knock loose the carbon inside.
If there is any exhaust leakage where the muffler connects to the cylinder, or if the muffler gasket appears damaged, replace the gasket. A muffler that is badly damaged, dented, cracked, or rusted must be replaced.