CLASSES FOR 2025

THESE REGULATIONS/CLASSES ARE IN ADDITION TO, AND NOT IN PLACE OF, THE ACU TECHNICAL REGULATIONS.

THE ORGANISERS RESERVE THE RIGHT TO IMPOUND ANY MACHINE, ITEM OF EQUIPMENT OR CLOTHING AT ANY TIME AND WITHOUT THE RIGHT OF PROTEST OR REFUND.

Open 80cc-450cc
Includes upto 500cc two-stroke machines. This class will run as a standalone championship but share a grid with the Minitwin Championship.

Minitwins
Any four-stroke minitwin made for road use. This class will run as a standalone championship but share a grid with the 80cc-450cc Championship.

Byron Cup
Open to all machines up to 500cc and 650cc minitwins made for road use.

Classic ERA
Open to any 501-1300cc machines manufactured pre-2000. This class will run as a standalone championship but share a grid with the Sport Twin Championship.

Sport Twins
Modified four-stroke supertwin, with water cooled engine up to 800cc, and Kramer 690, Yamaha 700, Aprilia 660, Suzuki 800 and Triumph 660. Minimum age of 16. This class will run as a standalone championship but share a grid with the Classic ERA Championship.

CB500
Open to all Honda CB500 and Kawasaki ER500 machines. No slick tyres permitted.

Pre-Electronic Injection
Up to 600cc and 601-1300cc machines. Generic and formula specifications.

Mallory Trophy
Open class up to 600cc. And 601cc to 1300cc. Only Clubman & National licences are eligible.

Open 600cc
Open to 600cc four-cylinder machines. Includes 675-798cc three-cylinder, and 890-959cc twin-cylinder.

EMRA Open
Open to all 597cc-1300cc machines. Generic regulations. Rookies eligible.

Novice/Rookies 175cc-1300cc
Rookies who have held a licence for no more than two years are eligible. Riders must not have held an ACU Licence before 1st January 2023. Exceptions to the above date by approval of the Secretary of the meeting. Riders who have passed their ACU CTC/BRA since 1st January 2023 AND who have upgraded to Clubman within this timeframe, will not be eligible. Riders who start the 2025 championship as a Novice and upgrade to Clubman during the season will remain eligible to finish the championship. Riders who finished in the top three of the Championship in 2024 are not eligible. Slick tyres are allowed only if the licence permits.

Formula 750 
For 650cc to 1000cc production-based British four-stroke twins and triples built up to December 1974. Unlimited engine tuning. Carburettors only. Pump fuel. Aftermarket period chassis permitted. 35mm forks. 18” or 19” wheels. Treaded tyres 110 front and 130 rear. No tyre warmers.

Sidecars 590-1000cc (April & September Only)
Open to four-stroke three-wheeler outfits upto 1000cc.

The onus of eligibility rests with the competitor.  
Eligibility can occasionally be granted on a case-by-case basis for machines across all championships that are within the spirit of the class.

PLEASE NOTE THAT SLICK, TREADED OR WET TYRES AND TYRE WARMERS CAN BE USED IN ALL CLASSES. (EXCLUDING CB500 WHERE NO SLICKS ARE PERMITTED AND F750 WHERE NO SLICKS OR TYRE WARMERS ARE PERMITTED).

NOVICE AND INTERMEDIATE NOVICE COMPETITORS ARE REQUIRED TO WEAR AN ORANGE VEST IN ALL RACES AND PRACTICE PERIODS.