Silencer (muffler)

The silencer (British term) or muffler (American term) is the last part of the exhaust system. It reduces noise by passing the gases through perforated tubes, packing material or baffle chambers. Many modern silencers also contain a catalytic converter.

Silencer design affects flow and pressure waves in the exhaust, so changing it can alter power delivery and fuelling. Aftermarket silencers are lighter, but on fuel-injected bikes may need remapping. Road-legal replacements must be type-approved (E-marked) and meet noise limits.

On two-strokes and off-road bikes the glass-fibre or steel-wool packing burns out over time, making the bike louder and harsher. Repacking is a simple, regular job. Check also for cracked mounts and loose rivets.