Legal exhaust noise level in the UK
There currently is a bit of a grey area around what is an acceptable noise level for an aftermarket exhaust. There is government legislation for motorcycle exhausts - specifically in The Road Vehicles Regulations 1986 and Regulation 97. These pertain only to the fact that an exhaust needs to be well maintained, and not to have been modified beyond it's regular state. Eu Directive 78/1015/EEC states that the limit of noise produced by a motorcycle should not exceed 86dB for a bike 500cc and above - and lists diagrams of how this reading should be measured. According to MCN, the current limit is 82-86dB, with the police using 90dB as a limit to take into account wear and tear. Many aftermarket exhaust companies have E marked exhausts and cans - this shows that they have submitted their exhausts for testing and approval by the EU. Those marked with 'race use only' or 'not for road use' will fail an MOT - it is also down to the MOT centre's discretion as to whether they think your exhaust is too loud, so it's well worth putting a baffle in when you take your bike for MOT to be on the safe side.
| Capacity (cc) | Noise Limit |
|---|---|
| 80cc and under | 78 dB |
| 125cc and under | 80 dB |
| 350cc and under | 83 dB |
| 500cc and under | 80 dB |
| 500cc and above | 86 dB |
Many race tracks also implement an exhaust noise limit - they can have communities/housing nearby to take into consideration. As a result, exhausts are often tested on the day to make sure you are meeting their limits. Generally most UK tracks have a standing Decibel test limit of 105dB, but this may vary. It's worth checking on the relevant track website or with the company that arranges the track day to verify the limit you'll have to adhere to.
This involves holding a testing device at a 45 degree angle, half a meter away from the exhaust exit. RPM varies depending on the bike and the number of cylinders, but it is generally 7000RPM for a 4 cylinder 600cc, 5500RPM for one over 750cc and 5000RPM for a twin cylinder over 750cc.
This is generally conducted at the start/finish line or at the point of the track that is most exposed to local residents. It tends to be taken from a distance of 10 metres.
| Track | Static Test | Ride By Test |
|---|---|---|
| Anglesey | 105 dB | - |
| Brands Hatch | 102 dB | 92 dB |
| Cadwel Park | 105 dB | - |
| Croft | 102 dB | 97 dB |
| Donington Park | - | 108 dB |
| Lydden Hill | 100 dB | 90 dB |
| Mallory Park | 103 dB | - |
| Oulton Park | 102 dB | 98 dB | Silverstone | 105 dB | 102 dB |
| Snetterton | 102 dB | 92 dB |