Its official Period Four vintage is now called F1 and will bring in most bikes to model year 89 allowing for heavy mods ala old Superbike rules.Here is a copy of the official rules draft as unveiled at the show. This is for the VRRA org and should bring VRRA closer to WERA as far as elegiable bikes is concerned and make it easier for cross border racing. 12/1/2003 VRRA PERIOD 4 - Structure recommendations 3 ‘Classes; 1. F1 2. F2 3. F3 Class structure: 1. F1. · Up to 1200cc air cooled four stroke · Up to 1000cc four stroke twins (L/C) § Up to 750cc three or four cylinder four stroke (L/C Includes oil) · Up to 750cc two stroke Grand Prix bikes 2. F2 § Up to 600cc four cylinder four strokes § Up to 500cc two stroke -any configuration based on production street bikes § Up to 750cc four stroke twins · Up to 350cc two stroke Grand Prix bikes · Up to 750cc air cooled four stroke multis · Unlimited cc liquid cooled singles 3. F3 § Unlimited cc air cooled four stroke singles § Up to 400cc two stroke street based twins and triples § Up to 500cc two stroke singles § Up to 400cc liquid cooled four stroke fours § Up to 650cc four stroke twins · Up to 550cc air cooled four stroke multis All frames and engines must be same design and appearance (without significant change) to machines available at cut-off date. All bikes in formula class must use bodywork of the period. This can be stock or aftermarket. Any machine using USD forks must have used them during the period. Forks must be the same brand and type used during and commercially available to the general public before the cut-off date of 1989.