Formula Vintage Classic: Class C, Class C Handshift,

10.3 FORMULA: Formula 750, Formula 500, Formula 250, Formula Vintage

10.3.1 FORMULA 750: Fully GP-kitted four-stroke machines up to four cylinders, manufactured as 600750cc and built prior to December 31, 1972, and like design. Among the eligible F750 motorcycles are: • BSA Rocket 3 & Triumph Trident “works” roadracers or replicas • BSA Rocket 3 & Triumph Trident “production” racer (i.e., Slippery Sam) • BSA “A-series” twins “production racer” • BMW “works” (pre-’75 season) • Ducati “works” V-twins (pre-NCR) • Honda CR & RC750 roadracers (with factory kit in stock frame and unmodified swingarm), single-cam type • Harley-Davidson XR750, iron and alloy motors, roadrace or dirt track frames • Laverda SFC • Moto Guzzi V7 Sport • MV, street-based 750 fours • Norton “FIM” production racers • Norton “John Player” replica street machines • Norton “works” JPS racers • Norton 750 twins “production racer” (later castings permitted) • Rickman Honda 750 • Rickman frames with various eligible engines • Seeley frames with various eligible engines • Triumph twins “production racer” • Yamaha XS650 Note: 450/500 Honda four-cylinder-based machines are not allowed, regardless of displacement.

10.3.1A REQUIREMENTS AND MODIFICATIONS FOR F750 a) Every effort must be made to duplicate the original “works” appearance. b) Fairings are required, at minimum a quarter-fairing. c) “Works” frames are required where appropriate, plus frames by Trackmaster, Champion, Seeley and Rickman are permitted. d) Disc brakes are allowed, though they must be period type (fixed steel disc, maximum 12-inch diameter, with two-piston calipers). e) Front forks with hydraulic anti-dive or external reservoirs are not permitted. Forks may be no larger than 38mm, unless supplied as OEM on that motorcycle. f) Weslake four-valve conversions for twins are allowed, as are Nourish-Weslake twin-cylinder engines. g) Appearance and workmanship of a reasonable standard shall be enforced. h) Modifications must be consistent with the spirit of the class. i) Maximum rim width: front, 2.5 inches (WM-4); rear, 3.0 inches (WM-5), except H-D XR750s, which are permitted to use a WM6 (3.5 inches) when fitted with original Morris Magnesium wheels. No Astralite wheels. j) Keihin CR Special carburetors are allowed, maximum 31mm for four-cylinders, 34mm for triples and 39mm for twins. Note: See requirements of all road racing motorcycles in Section 9.

10.3.2 FORMULA 500 Two-strokes and certain four-strokes to 500cc. All motorcycles must be fully GPkitted. The cutoff date is December 31, 1972. Like-design models are also permitted. Among the eligible motorcycles are: • Bridgestone 350 Daytona GTR • HD RR/Aermacchi 250 • Honda SOHC fours to 550cc, DOHC twins to 550cc • Kawasaki H1R, H1RA • Kawasaki 350 A7R, A7RA • JML (Kimtab 429) with wire wheels • Suzuki 500 Titan factory racer, GT380 and GT550 • Yamaha RD350 and RD400 (air-cooled models only), TR2, TR3 and R5based TR replicas • Yamaha TX500, TX500A • Yamaha TZ250 Twin Shock

10.3.3 FORMULA 250 Two-stroke twins up to 250cc, two-stroke singles to 360cc, four-stroke singles to 350cc, Honda CB350 twins and Honda CB350F fours. All motorcycles must be fully GP-kitted. The cutoff date is December 31, 1972. Like-design models also are permitted. Among the eligible motorcycles are: • Bridgestone 175, 200 • Bultaco, pre-1973 up to 360cc • Bultaco, 350cc AJR replicas • Can-Am, pre-1973 250 (57.5 mm stroke, aluminum, or magnesium cases) • H-D/Aermacchi, pre-1973 (two- and four-stroke) • Honda CB350K twin, CB350 four, CB400F four with original stroke and bore (.040” overbore permitted) • Kawasaki A1R, 350 Bighorn single, F5, F9, S1 • Maico 175cc air-cooled single • Montesa, pre-1973 up to 360cc • Ossa, pre-1973 250 • Suzuki 250 X6, GTX, GT, T250, T200 • Yamaha RD125, RD200, RD250, TD2, TD2B, TD3, TA250, TA125, RD56/ TD1 “works special”

10.3.4 FORMULA 125 Air-cooled, twin-shock, steel-framed Grand Prix motorcycles up to 125cc, plus certain GP-kitted street and enduro machines. Major components (and modifications) must be consistent with those used in the 1960s and ‘70s. The following motorcycles are eligible for this class; if not included on this list, approval must be obtained from the Vintage Roadrace Rules & Eligibility Committee: • Bridgestone 200cc twin • Bultaco, up to 200cc • Can-Am 125, 175 • Honda MT125, MT125R, 200cc four-stroke twin • Husqvarna 175, 1975-’82 • Kawasaki F7 • Maico RS125 • Montesa, up to 175cc • Ossa, up to 175cc • Suzuki GT185, TS125/185 • Yamaha TA125, AT1/2/3, DT125, RD125 • Yamaha YCS1, CS3/5, CT1/2/3, DT175, RD200 Maximum carburetor or restrictor plate size for 175cc singles is 34mm; maximum carburetor or restrictor plate size for 180-200cc two-stroke twins is 22mm. (See rule 9.7.14b). 10.3.5 FORMULA VINTAGE Eligible motorcycles include any 500 Premier, Formula 500, Formula 750, or Sportsman 750 machine. Additionally, the following motorcycles, up to model-year 1982 (and like design, except where specifically noted) are eligible: • Honda CB550 four-cylinder • Kawasaki H2R 750, KR750 • Suzuki RG500, through 1987 • Suzuki GT750, TR750 • Yamaha RZ350, all years, including Canadian and Brazilian models • Yamaha RZ500, through 1987 • Yamaha TZ250, through 1984 • Yamaha TZ350, TZ500, TZ750 a) Frames must be of period-design tubular steel, or OEM street-based aluminum frames (e.g., RG500) from specifically-allowed motorcycles. There is no displacement limit on 250/350cc-based twins. Wheels, forks, and brakes to follow Vintage Superbike Heavyweight rules. b) Modern treaded tires and slicks allowed. Rain tires allowed. Note: If you believe a machine would fit into this class but is not listed, please submit an eligibility request form found near the end of this Handbook. 10.3.6 REQUIREMENTS AND MODIFICATIONS FOR FORMULA 125/250/500 a) All machines must be no-compromise Grand Prix racers (i.e., clip-on, or low, narrow handlebars; no lighting equipment or related brackets, except that factorywelded brackets may be retained if desired; no street equipment of any kind, including brackets). Electric starters allowed if originally equipped.