Classic 50cc Regulations

Classic 50cc

General Requirements: 

ALL machines must comply with ACU Standing Regulations. 

This is Classic orientated road racing for machines of the style and type used up to the cutoff date of 1983 when the 50cc GP ceased to be a class. 

It is the rider’s responsibility to make sure that his machine is presented in a clean, tidy and safe condition at each meeting with particular attention to safety critical components such as brakes, for example when engines have been upgraded in existing chassis. 


Steel tube, Aluminum Monocoque or plate types are allowed, No modern or twin-spar types allowed. 

NO upside down forks are allowed. 


Twin pot/piston Disc Brakes are permitted but must be of period appearance, no modern wavy discs allowed. Maximum diameter of disc is 240mm. 


17″ & 18”diameter wheels with WM1 or 1.6 maximum rim widths. 


Maximum width 85mm when fitted. Tyre warmers, slicks, and cut slicks are not permitted. 

Treaded tyres including wets can be used. 


Air and Water-cooled, manual gearbox with a minimum of 3 gears and a maximum of six. 

50cc and/or within manufacturers oversized piston sizes. This also applies to 4-stroke machines. 

Carburetor can be any type but electronic power jets are not allowed. 

Ignition can be any type but modern looking components should be hidden. 

Due to some older machines needing re-bores, or a mixture of parts to keep them in running order, a greater tolerance may be allowed with a maximum allowance of 5% on steel barrels, but this must be agreed by the Race Director prior to racing. 

 Race Numbers: 

Black numbers on white backgrounds. 


Any bodywork representative of the classic pre 1983 style period can be used. 

Any carbon fibre must be painted in a solid colour. 

Rain Lights Must be fitted and functional. 

 Engine Capacity Checks. 

Random engine capacity checks may be done at a race meeting as requested by the Officials on the day.