Exhaust System

The exhaust system takes the hot burnt gases from the cylinder head and releases them behind the bike. It typically consists of header pipes (downpipes), often a collector, a catalytic converter on modern road bikes, and one or more silencers (mufflers). Two-strokes use an expansion chamber that is tuned to boost power at certain revs.

Exhaust design affects power delivery, sound and emissions. An aftermarket exhaust may save weight and change the character of the engine, but often needs ECU or carburettor adjustment.

In the EU, road-legal exhausts must be E-marked and meet noise and emission limits; removing the db-killer or catalytic converter can fail inspection. Check for leaks at the header joints (a ticking sound), rust, loose brackets and, on off-road bikes, repack the silencer regularly.