GP 250/SSP 400   ( Class 1 )   until 250ccm 2Strokes -- until 400ccm 4Strokes 4Valves -- until 900ccm 4Strokes 2Valves -- Single cylinder
SSP = SuperSport ( Class 2 )  until 636ccm 4Strockes 4cylinders -- until 750ccm 4Strockes  2cylinders -- until 500ccm 2Strockes
R6, CBR 600, ZX 6, GSX R 600, Ducati 748, 749
SBK = SuperBike ( Class 3 )   until 750ccm 4Strokes 4cylinders -- until 1000ccm 4Strokes  2cylinders  
Ducati 916-999, Aprilia Mille, TL 1000, VTR-SP1, GSX R 750, ZXR 750
STK = StockSport ( Class 4 )  over 750ccm 4Strokes 4cylinders -- over 1000ccm 4Strokes  2cylinders  
R1, CBR 900, ZX 9, GSX R 1000