an old man returns Wrote:"Applies to Paton 500cc GP twin: The use of any externally fitted oil pump is prohibited. Exhaust
systems must be of the �low level� type as fitted originally. The use of disc brakes is prohibited.
Implementation � wef 01/12/07

Applies to all up to 500cc Group 1 Period 1 & 2 machines: Only the following rear tyres may be fitted:

1) Any 19� tyre

2) The following 18� tyres: a) Dunlop 3.50 x 18, 3.50/3.25 x 18 KR124 and KR124A

b) Avon AM22 110/80 x 18 Rear Fitment.

Please note that all tyres must conform to ACU and CRMC regulations. Maximum rim size WM3.
The decision of the sub committee is final.
Implementation � wef 01/12/07"

Direct from CRMC web site, will the MGP rules follow their direction?

The MMCC have largely used the CRMC formulae, but be careful what you quote. Senior MGP machinery is mostly Group 1, period 2. These are allowed more latitude eg the use of disc brakes.

http://www.crmc.co.uk/2008/CRMC%20Eligib...202008.pdf