MCI Guide to Moped and Motorcycle Exhaust System Markings
guide is set up to help the police identify illegal exhausts on
mopeds and motorcycles in England. It is designed to identify the
main problems of exhausts today from noise to custom fitted performance
enhancing extras. The report is split into several sections to point
out the most common failings on exhausts in order for the police
to prosecute persistent offenders.
This report can also help all bikers by showing, what is legal and
what is not. By keeping to these set guidelines set by the Department
for Transport you can keep you motorcycles/mopeds legal on the road.
The noise limits imposed on new motorcycles have been very
stringent for many years. Certainly any motorcycle fitted
with an efficient original equipment (OE) or replacement exhaust
system (RESS) is most unlikely to cause offence or be illegal.
This means that if a motorcycle "sounds noisy", its exhaust
system is probably illegal and is worth inspecting for the
Illegal Exhaust Systems
These generally fall into two categories; the poorly maintained,
and more commonly, the "race or custom system". The later
are in widespread use and are particularly popular among the
riders of "race replica" and "custom or "chopper" style machines.
Race and illegal custom silencers should bear the marking
"not for highway use" or similar wording, however this may
have been erased or removed. It is therefore highly probable
that the exhaust system of a "noisy bike" will either be unmarked
or have "not for highway use" marked on it. Either way these
are evidence of an offence.
Markings and their Locations
These are required to be "indelible and clearly legible, even when
fitted to the vehicle" (C&U and 92/61 Annex V). A popular practice
among illegal RESS manufacturers is either to use chrome foil stickers
or to "hide" the markings on the inward face of the silencer or
in another inconvenient location.
Table 1: Original Equipment Silencer Marking (mopeds and motor
This table refers to the exhaust Systems fitted to machines when
they were made.
2: Marking requirements for mopeds and motor cycle silencers in-use
This table refers to the markings that should be on any motorcycle,
scooter or moped being use on the road except for machines first
registered before January 1st 1985
3: Marking requirements for silencers/exhaust systems at Point of
All replacement silencers/exhaust systems offered for sale must
4: Noise Limits for Motorcycles (for Information only)