Motorcycle exhaust close upInformation on marking requirements and decibel levels

Lost Your Motorcycle Exhaust Identification?  Have your exhaust pipe markings disappeared, are they obscured by age,
wear and tear, crash damage or simply polished off?

MOT legislation requires that the vehicle tester is able to see that the standard (original makers stamp), or aftermarket exhaust fitted to the bike, is marked with the obligatory BSAU 193a and the European “E” mark.  If your Exhaust can does not carry these markings, it could lead to a failed MOT and if you are stopped by the Police it can lead to a fine and points on your licence.

The law says that your bike will fail the MOT if:-
a. Any part of the exhaust system is missing or excessively deteriorated.
b. A leak in an exhaust system which causes excessive noise to be emitted.
c. An exhaust system mounting missing or one which is in such a condition that it does not fully support the exhaust system.
d. silencer which is in such a condition or is of such a type that the noise emitted is clearly in excess of that which would be produced by a similar machine fitted with a standard silencer in average condition.
e. A silencer fitted to a motorcycle first used on or after 1 January 1985 which is not marked with either:-
* The make and type specified by the motorcycle manufacturer.
* British Standard classification BSAU 193 or BSAU 193a or an EEC approval number prefixed by a small ‘e’ marking or an ECE approval number prefixed by a capital E.
* A silencer marked ‘NOT FOR ROAD USE’, TRACK USE ONLY’ or similar words.

There are businesses around which will sell you stickers and / or plates which could be used to cover-up unwanted graphics and wording on the exhaust pipes.  However, these tags should not be fitted to a non standard can or exhaust to try and break the law or pass it off as legal for an MOT.

Exhausts – on motorcycles first used on or after 1 January 1985 the silencer which forms part of the exhaust system must be either:

(i) that with which the machine was first fitted; or

(ii) clearly and indelibly marked with :-

-the relevant BS marking BS AU 193/T2, BS AU 193a, 1990/T2, BS AU 193a, 1990/T3; or

  • the relevant “e” marking to show compliance with EC Directive 89/235; or the relevant “e” marking to show compliance with Chapter 9 of EC Directive 97/24; or
  • the name or trade mark of the manufacturer or marked with that manufacturer’s part number – relating to it.

The European Community noise limits applicable to new motorcycles first used from 1 April 1991 are:

Motorcycle Category by cm3 Limits in dB(A)
Up to and including 80 77
Between 80 and 175 (incl.) 79
Above 175 82

Motorcycles approved to EU Directive 97/24/EC, Chapter 9 will be 2dB(A) less than the above figures.

(Note: the precise regulations for motorcycle exhausts are complex and it is recommended that they are studied closely to obtain accurate and complete details of the requirements).

Before buying any replacement parts for systems listed in this section, riders should check for the relevant marks, where applicable. These will include an “e” mark for EC Directives, an “E” mark for ECE Regulations and “BS” for British Standards.

(Note: amateur motorcycle builders may be exempt from some or all of the requirements)



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