Vintage Superbike

c) 250 GRAND PRIX: 1968 and earlier 250cc four-stroke machines; 250cc aircooled, single-cylinder two-strokes with a maximum of five speeds; 175cc liquidcooled two-stroke singles; 175cc air-cooled, twin-cylinder, two-strokes with a maximum of six speeds. See Section 10.2.4. d) 200 GRAND PRIX PLUS: This class combines a variety of engine designs and displacements, based on an index of performance. See Section 10.2.5. e) FORMULA 750: Fully GP-kitted four-stroke machines up to four cylinders, manufactured as 600-750cc and built prior to December 31, 1972.

See Section 10.3.1. f) FORMULA 500: Fully GP-kitted two-stroke and certain four-stroke machines up to 500cc, based on an index of performance. See Section 10.3.2. g) FORMULA 250: Fully GP-kitted two-stroke air-cooled machines, including singles up to 360cc and twins up to 250cc, and certain four-strokes.

See Section 10.3.3. h) FORMULA 125: Air-cooled, twin-shock, steel-framed Grand Prix bikes up to 125cc, plus certain GP-kitted street and enduro machines. See Section 10.3.4. i) FORMULA VINTAGE: Open to machines eligible for 500 Premier, Formula 750, Formula 500, and Sportsman 750. Additional models are eligible; for the complete listing, see Section 10.3.5. j) CLASS C: Intended for AMA “Class C” machines manufactured prior to December 31, 1951, as ‘51 models. Also, CLASS C HANDSHIFT, a championship class run together with, but scored separately from, Class C.

See Section 10.4.1. k) PRE-1940 GRAND PRIX: 1940 and earlier Grand Prix or modified street machines, including 500cc OHV and OHC, and 750cc sidevalve machines.

See Section 10.4.2. l) CLASSIC SIXTIES: 1960s-era and earlier Grand Prix/Clubman 350-500cc fourstroke OHV and OHC, and 750cc sidevalve machines.

CLASSIC SIXTIES 650: 1960s-era 650cc OHV and 883cc sidevalve machines, run with but scored separately from Classic Sixties. See Section 10.4.3. m) SPORTSMAN: 1972 and earlier four-stroke, street bike-based machines, divided into 350, 500 and 750cc classes. See Section 10.5. n) NOVICE HISTORIC PRODUCTION: 1978 and earlier production street machines with the standard OEM frame, swingarm, fork and handlebar mounts.

Engines use the original OEM bore and stroke. Classes are Lightweight (fourstrokes up to 500cc, 250cc two-strokes and certain 350cc two-strokes) and

Heavyweight (four-strokes up to 750cc and 350-500cc two-strokes). This class is intended for novice riders. See Section 10.6. o) BEARS® (BRITISH EUROPEAN AMERICAN RACING SERIES): Twocylinder pushrod machines built up through 1968, competing under Formula 750 specifications. See Section 10.7. p) SIDECAR: Vintage and modern three-wheeled machines. See Section 10.10. q) EXHIBITION: Non-competitive exhibition or “rolling display” rides. See

Section 10.11. Guidelines available from theAHRMANational office.

8.2 VINTAGE SUPERBIKE

a) HEAVYWEIGHT: Unlimited displacement twins and pushrod triples, and displacement-limited fours and sixes built up through the 1982 model year.

See Section 10.8.3.