SECTION 10 - REQUIREMENTS FOR ROADRACING
CLASSES

10.1 PERFORMANCE INDEX: When a motorcycle is demonstrably faster or slower than others in its displacement group it may, at the discretion of the review committee, be assigned to another class.

10.2 GRAND PRIX: 500 Premier, 350 GP, 250 GP, 200 GP Plus
Fully GP-kitted motorcycles built prior to December 31, 1968. Four-strokes only in 500 Premier; two-strokes permitted in 350, 250 and 200 GP. Drum brakes only. Fairings are encouraged but not mandatory. Engine modifications are not limited as long as period components are used and class displacement is not exceeded. Gardner carburetors are allowed for 500 Premier and all GP.
Each of the above classes has its own eligibility listing, requirements and restrictions. All of these classes must also comply with rules 10.2.5a–l. Please note that in some cases those machines listed with an asterisk (*) will have special instructions listed below. If for some reason your machine does not comply with the year cutoffs and is not listed in the class as eligible, you must submit an Eligibility Request Form at least 10 days before an event in which you intend to compete.
10.2.1 500 PREMIER: Any fully GP kitted 500cc OHV/OHC or 750cc sidevalve four-strokes built before December 31, 1968, and like design. Among the eligible machines are:

Benelli, “works” fours
Bianchi 500 “works” twin
BMW Rennsport
BSA 500cc twin or single “works” or replica
Dick Mann frame with G50 or other period engine
Ducati 450 single
Ducati 500cc bevel-gear V-twin “works” racer and accurate replicas
Eso 500 single
Gilera
Harley-Davidson KR roadracer
Honda CR450 roadracer
Honda-Drixton 450
Jawa “works” twin
Jawa 500 single
Linto
Matchless G50
McIntyre Special and replica, G50 powered
Moto Guzzi single, twin and V8
MV triple
MV four, early wide-angle head (pre-1973 era)
Norton Dominator Daytona 500 or replica
Norton Manx
Paton twin (8-valve Paton twin not legal for 500 Premier)
Rickman GP roadracing frame, powered by G50 or other period engine
Royal Enfield Bullet built in India, four- or five-speed models
Seeley frame with G50 or other period engine
Triton
Triumph 500cc twin “works” or replica; Weslake four-valve heads permitted
Velocette Thruxton and Venom Clubman
Vincent Grey Flash or replica
Weslake (Nourish) pre-unit engines
NOTE: Honda CB/CL/SL 350 twins are not eligible for this class. See 350 Sportsman or Formula 250.

10.2.2 350 GRAND PRIX: Any of the following types of fully GP-kitted motorcycles built before December 31, 1968, and like design: 350cc OHV/OHC four-stroke; 350cc air-cooled single-cylinder two-stroke; 250cc water-cooled, single-cylinder two-stroke; 250cc air-cooled twin-cylinder two-stroke. Among the eligible machines are:

Aermacchi 350 four-stroke single roadracer
AJS 7R
Bianchi “works”
Benelli twin “works” roadracer and fours
BSA 350 OHV single
Bultaco 250 water-cooled single, round cylinder type only
Ducati 350 narrow and wide case
Gilera
Harley-Davidson ER/CRTT four-stroke roadracer
Honda CR77 “works” or replica, CB77 fully race-kitted; CB350F with original bore and stroke (.5mm overbore permitted), must be serious GP replica, fully GP-kitted with race tank and seat, full fairing and four-into-four exhaust
Jawa “works” twin roadracer
Kawasaki A1R (not A7RA) twin, maximum 250cc
McIntyre Special and replica, 7R powered
Moto Guzzi single
Moto Rumi “works” or replica
MV triple
MV four, early wide-angle head (pre-1973 era)
MZ “works” 250 twin
Paton twin
Rickman GP roadracing frame, powered by H-D ER/CRTT or AJS 7R
Seeley 7R, or other period engine
Suzuki X6 with racing exhaust
Triumph Tiger 80, 90 350cc twin
Yamaha; no updating beyond TD1-C. Original carburetors may be replaced with 26mm Mikuni VM-type round-slide; power jets may not be in operation.
NOTE: Honda CB/CL/SL 350 twins are not eligible for this class. See 350 Sportsman or Formula 250.

10.2.3 250 GRAND PRIX: Any of the following types of fully GP-kitted motorcycles built before December 31, 1968, and like design: 250cc OHV/OHC four-stroke; 250cc air-cooled single-cylinder two-stroke; 175cc water-cooled, single-cylinder two-stroke; 175cc air-cooled twin-cylinder two-stroke. Among the eligible machines are:

Aermacchi 250 four-stroke single roadracers
Benelli 250 four-stroke single roadracer
Benelli 250 four-cylinder, street-bike based replica
Bridgestone 175cc twin
Bridgestone 200cc, maximum 24mm carburetors
BSA B25 & C15 single
Bultaco Metralla (round cylinder type only), race kitted
Bultaco TSS air-cooled single (round cylinder type only), maximum 5 speeds
Cotton Conquest or Telstar
CZ single “works” replica
Ducati MkI, Diana, MkIII, F-3, narrow and wide case
Greeves Silverstone
Harley-Davidson CRTT four-stroke roadracer
Honda CR72 “works” or replica, CB72 fully race-kitted
Honda “works” four or six
Montesa Impala
Moto Rumi “works” or replica
Motobi production racers
NSU Sport Max
Ossa 250 single
Parilla production racer
Rickman GP roadracing frame powered by H-D CRTT
Suzuki X6 with OEM street exhaust and silencers
Triumph Tiger 70, TR25W, T25T, single
Yamaha CS3 and CS5

10.2.4 200 GRAND PRIX PLUS: This class combines a variety of engine designs and displacements, based on an index of performance. Eligible machines are listed below by make, model, displacement, and individual restrictions. Like-design models also are permitted. Displacement as noted below may not be increased beyond the allowable overbore. (See rule 9.7.2).

Aermacchi/H-D 250cc long-stroke (66mm bore x72mm stroke), wet clutch, original backbone chassis, maximum 30mm carburetor (i.e., up to 1965 only)
AJS/Matchless 250cc pushrod single, maximum 30mm carburetor
Ariel Arrow 250cc twin, original frame and forks, one 32mm or smaller carburetor
Benelli 250cc pushrod single, maximum 30mm carburetor
BMW R26 250cc single, maximum 30mm carburetor
Bridgestone 175cc twin, maximum 22mm carburetors
BSA/Triumph 250cc single, maximum 30mm carburetor
Bultaco 125cc water-cooled GP TSS (round barrel only)
Bultaco 175cc air-cooled single (round barrel only), maximum 30mm carburetor
Bultaco 200cc air-cooled single, maximum 4-speed, maximum 28mm carburetor
Ducati 125, 160, 175, 200cc single
Hodaka 125cc
Honda CR110 (CR93)
Honda CB/CL 160, 175cc twin
Honda CA/CB 125, 160cc twin
Indian Arrow 250cc single, maximum 30mm carburetor
Moto Guzzi 250cc pushrod, maximum 30mm carburetor
MV 200cc “works” or replica single or twin
MV Augusta 250cc pushrod, maximum 30mm carburetor
Norton 250cc pushrod twin, maximum 30mm carburetor
Ossa 175cc, maximum 30mm carburetor
Parilla 250cc pushrod, maximum 30mm carburetor
Parilla 200cc production racer
Puch/Allstate 250cc split single, maximum one 32mm carburetor
Rumi 125cc flat twin
Triumph 200cc T20 Tiger Cub, maximum 250cc with allowable overbore; maximum 30mm carburetor
Villiers-based 250cc two-strokes such as Cotton, DKW, Greeves, maximum 32mm carburetor
Yamaha AS1 125cc twin (pre-1968), cast iron cylinders only
Yamaha CT1 175cc single (no Noguchi engine components), maximum 30mm carburetor
Yamaha YCS1 180cc twin (pre-1969), maximum 22mm carburetors.

10.2.5 REQUIREMENTS AND MODIFICATIONS FOR GRAND PRIX CLASSES
a) All GP class motorcycles must be fully GP kitted, with no lights, no starting mechanisms, no street equipment or associated brackets (factory-welded brackets may be retained if desired), low narrow handlebars (maximum width 32 inches). Fairings are encouraged.
b) Frame may be changed to racing type, though must be period type and style. (Refer to rule 9.7.3)
c) Front forks may be changed, though must be period type and style. “Ceriani” type may be no larger in diameter than 35mm, unless supplied as OEM on that motorcycle.
d) Period retrofit gearboxes are permitted (i.e., Quaife, Shaflieghtner). Maximum 6 speeds unless otherwise stated.
e) Front disc brakes are prohibited. Rear disc brakes are permitted, provided they are period equipment.
f) Magnesium engine cases are allowed in 500 Premier.
g) The number of valves in the cylinder head may not be increased or decreased from stock.
h) No more than one carburetor per cylinder.
i) All modifications must be consistent with the spirit of the class and period.
j) Appearance and workmanship of a reasonable standard shall be enforced.
k) Two-strokes must use silencers.
l) Maximum rim width WM3 in all GP classes
NOTE: See requirements of all roadracing motorcycles in Section 9.

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 600-750cc and built prior to December 31, 1972, and like design. Among the eligible F-750 motorcycles are:

BSA Rocket 3 & Triumph Trident “works” roadracers or replicas
BSA Rocket 3 & Triumph Trident “production” racer (i.e., Slippery Sam)
BSA “A” twins “production racer”
BMW “works” (pre-’75 season)
Ducati “works” V-twins (pre-NCR)
Honda CR & RC 750 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”
NOTE: 450/500 Honda four-cylinder based machines are not allowed, regardless of displacement.

10.3.1A REQUIREMENTS AND MODIFICATIONS FOR F-750:
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 38 mm, 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, WM3 (2.15 inches); rear, WM5 (3 inches), 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 as like-design on CR750 Hondas (or replicas), maximum 31mm.
NOTE: See requirements of all roadracing motorcycles in Section 9.

10.3.2 FORMULA 500: Two-strokes and certain four-strokes to 500cc. 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 350 Daytona GTR
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 R5 based TR replicas
Yamaha TX500, TX500A

10.3.3 FORMULA 250: Two-stroke twins up to 250cc, two-stroke singles to 360cc, 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
Can-Am, pre-1973 250 (57.5 mm stroke, aluminum or magnesium cases)
H-D/Aermacchi, pre-1973 (two-stroke)
Honda CB350K twin, CB350 four, CB400F four with original bore and stroke (.5mm 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 two-stroke motorcycles up to 125cc plus certain listed 200cc machines. The cutoff date is December 31, 1972. Like-design models also are permitted. Among the eligible motorcycles are:

Bridgestone 200cc twin
Bultaco 200
Can-Am 125, 175
Honda MT125, 200cc twin
Maico RS125
Montesa 200
Ossa 200
Yamaha TA125, CS2 180. RD200, limited to 24mm carburetors or a minimum 1/8-inch restrictor plate with a 24mm opening (see rule 9.7.14b)

10.3.5 FORMULA VINTAGE: Includes 500 Premier, Formula 750, Sportsman 750 and Formula 500. Also includes Honda CB550 four-cylinders.
NOTE: If you have a machine you believe would fit into this class but is not listed, submit an eligibility request form.

103.6 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 factory-welded brackets may be retained if desired; no starting mechanisms; no street equipment of any kind, including brackets).
b) All machines must be equipped with racing exhaust systems; silencers are required on two-strokes and encouraged on others.
c) Any drum brakes (front or rear) of the period are permitted.
d) One front rigid-mounted steel disc brake may be used on F-125 and F-250 machines, and two front rigid-mounted steel discs on F-500 machines. Calipers must be period type with a maximum of two pistons. Late-model alloy types are prohibited.
e) Rims - Formula 500: Wheel rim diameter must be at least 18 inches and not exceed WM3 (2.15 inches) front and WM5 (3.00 inches) rear. Formula 250: Wheel rim diameter must be at least 18 inches and not exceed WM3 (2.15 inches) front and WM4.5 (2.75 inches) rear. Formula 125: Wheel rim width must not exceed WM3 (2.15 inches) front and rear.
f) Honda four-cylinder machines may use Keihin CR Special carburetors in all Formula classes. Maximum 26mm for CB350/400 fours in Formula 250 and Formula 500.

10.4 CLASSIC: Class C, Class C Handshift, Pre-1940 GP,
Classic Sixties

10.4.1 CLASS C: This class is intended for AMA “Class C” motorcycles and other for-sale, production- based machines of the period that existed up to and including 1951. Like-design models also are permitted. Class C Handshift is a championship class scored separately from, but run together with, Class C. 750cc sidevalve (45.7 cu. in.), 500cc OHV/SOHC/DOHC (30.5 cu. in.), plus .080” overbore. All major components must be OEM parts that existed prior to 1951, or accurate, detailed replicas of the same parts using the same type materials and technologies, unless specifically noted below. The burden of authenticating is upon the rider. Press clippings and photos with identifiable date may be helpful. There are no restrictions on internal modifications, except the stroke may not be changed from the original specifications and the bore may not exceed the .080” overbore limit.

10.4.1A REQUIREMENTS AND MODIFICATIONS FOR CLASS C
a) All 750cc machines must use hand-shift gearboxes.
b) Norton swingarm or “featherbed” frames are not permitted.
c) Hydraulic dampers may be used in place of springs on springer or girder forks as a safety measure. It is strongly encouraged that such damper units be “camouflaged” (e.g., springs painted flat black) to give more of a period appearance. Hydraulic rear dampers are prohibited unless such units were original equipment on that particular model of motorcycle.
d) All machines must use the OEM or period carb. If these carburetors are not available, machines are limited to the following:
1) Single-cylinder/single carb - Dell’Orto SS1, Amal GP or Amal Monobloc to 32mm (11/4”). Amal Mk1 Concentric (600, 900 or 1000 series) to 34mm (15/16”).
2) Twin-cylinder/single carb - Dell’Orto SS1, Amal GP or Amal Monobloc to 30mm (13/16”). Amal Mk1 Concentric (600 or 900 series) to 32mm (11/4”).
3) Twin-cylinder/twin carb - Dell’Orto SS1, Amal GP, Amal Monobloc or Amal Mk1 Concentric (600, 900 or 1000 series) to 28mm (11/8”).
4) 750cc sidevalve machines must use one OEM or exact replica butterfly-type carburetor, or abide by the above single-carburetor rule.
e) Wheels and brakes: Minimum wheel diameter is 16 inches. Maximum rim width is WM3 (steel or alloy). Wider steel rims are acceptable if they were provided as original equipment on that model. Wire-spoke wheels and drum brakes are required on both wheels. Brakes must be OEM equipment. Or, if changed, brakes must be single-leading/single-trailing shoe type. Maximum brake diameter is 8.75 inches, and maximum shoe width is 1.75 inches.
f) Machines must use OEM or period type transmissions of no more than four speeds. 750cc sidevalve machines must use a three-speed transmission.
g) Safety bars, stands, lights and mufflers must be removed.
h) Fairings or streamlining are not permitted. The front number plate must be parallel with the front fork angle.
i) Total-loss oiling is not permitted. Oil must not be deposited on the track.
j) Triumph pre-unit 500cc twins may use 650cc crankshaft but must not exceed .020” overbore.
k) The throttle must be self-closing, and a handlebar-mounted kill switch included.

10.4.2 PRE-1940 GRAND PRIX: This class is intended for 1940 and earlier GP and modified street machines, up to and including 500cc OHV and OHC, or 750cc sidevalve machines. Like-design models also are permitted. All major components must be OEM parts that existed prior to 1941, or accurate, detailed replicas of the same parts using the same type materials and technologies, unless specifically noted below. The burden of authenticating is on the rider. Press clippings and photos with identifiable dates may be helpful. There are no restrictions on internal modifications. However, the bore may not be increased more than .080”.

10.4.2A REQUIREMENTS AND MODIFICATIONS FOR PRE-1940
a) All machines must use the OEM or period carb. If these carburetors are not available, machines are limited to the following:
1) Single-cylinder/single carb - Dell’Orto SS1, Amal GP or Amal Monobloc to 32mm (11/4”). Amal Mk1 Concentric (600, 900 or 1000 series) to 34mm (15/16”).
2) Twin-cylinder/single carb - Dell’Orto SS1, Amal GP or Amal Monobloc to 30mm (13/16”). Amal Mk1 Concentric (600, 900 or 1000 series) to 32mm (11/4”).
3) Twin-cylinder/twin carb - Dell’Orto SS1, Amal GP, Amal Monobloc or Amal Mk1 Concentric (600 or 900 series) to 28mm (11/8”).
4) 750cc sidevalve machines must use one OEM or exact replica butterfly-type carburetor, or abide by the above single-carburetor rule.
b) Wheels and brakes: Minimum wheel diameter is 16 inches. Maximum rim width is WM3 (steel or alloy). Wider steel rims are acceptable if they were provided as original equipment on that machine. Wire spoke wheels and drum brakes are required on both wheels. Brakes fitted as standard equipment may be used, or they may be updated to Class C specification.
c) Gearboxes must not have more than 4 speeds.
d) Safety bars, stands, lights and mufflers must be removed.
e) The throttle must be self-closing, and a handlebar-mounted kill switch included.
f) Fairings and streamlining are not permitted. Front number plates must be parallel with the front fork angle.
g) Total-loss oiling is not permitted. Oil must not be deposited on the track.
h) OEM superchargers are permitted (see rule 9.7.2b).
i) Hydraulic dampers may be used in place of springs on springer or girder forks as a safety measure. It is strongly encouraged that such damper units be “camouflaged” (e.g., springs painted flat black) to give more of a period appearance. Hydraulic rear dampers are prohibited unless such units were original equipment on that particular model of motorcycle.

10.4.3 CLASSIC SIXTIES: This class is intended for 1960’s era and earlier “Grand Prix” and “Clubman” racers (and later machines of like design), 350cc/500cc OHV and OHC or 750cc sidevalve machines. Classic Sixties 350 is a non-championship class. All major components must be OEM parts that existed in that era, or accurate, detailed replicas of the same parts using the same type materials and technologies. The burden of authenticating is upon the rider. Press clippings and photos with identifiable dates may be helpful. Among the eligible machines are:

AJS 7R
BSA DBD Gold Star
BSA A7 twin
Gilera Saturno
Harley-Davidson KR 750SV (no “lowboy” frames), with stock exhaust only
Matchless G50
Matchless G45 and accurate replicas
Norton Daytona Dominator 500
Norton Manx
Norton International
Royal Enfield Bullet built in India, four-speed; five-speed models permitted only if the transmission is mechanically limited to four speeds
Triton (pre-unit 500 Triumph engine in Norton Featherbed frame)
Triumph T100 pre-unit
Triumph T100 unit-construction; must use stock frame, pre-1966 bushing engine, period squish chamber cylinder head, maximum 28mm carbs and conform to all other Classic Sixties rules. It is not necessary to use the distributor ignition.
Velocette Thruxton and Venom Clubman
Velocette KTT and KSS
Vincent Grey Flash

All non-unit British 650cc OHV machines.
All European 650cc OHV machines
Unit-construction BSA 865s up to 650cc in clubman trim
Unit-construction long-rod Triumph 650s in clubman trim
Harley-Davidson KH 55-cubic inch side-valve
Kawasaki W1
NOTE: Unit construction British machines may not use 1971-later OEM oil-bearing frames.

10.4.3A REQUIREMENTS AND MODIFICATIONS FOR CLASSIC SIXTIES
a) Cylinder bore may not be increase over .080” for singles and .060” for twins.
b) The stroke must remain stock.
c) All machines must use period-type carbs or Amal MkI Concentric (600, 900 or 1000 series) except eligible sidevalve machines, which may use one (1) Mikuni round-slide carb. BSA A65 and Triumph unit 650s in Classic Sixties 650 are restricted to 32mm carburetors, maximum one per cylinder.
d) Gearboxes must be mechanically restricted to 4 speeds.
e) Primary drive may be original-type chain, with chain guard (oiler must not operate). Belt conversions are encouraged, but must be fully enclosed and hidden from view (see rule 9.7.2j).
f) Oil must not be deposited on the track.
g) Brakes must of the period - two-shoe type drum. Later model BSA and Triumph drum brakes are allowed. (Norton Manx may use original four-shoe, 7-inch front brakes.) Minimum wheel diameter is 18 inches; maximum rim width is WM3. OHC machines must use minimum 19-inch wheels, front and rear.
h) Forks and rear shocks (or rigid rear end) must be of the period. Ceriani forks are prohibited.
i) All machines must be GP or Clubman racers in essentially factory-standard trim.
j) Throttles must be self-closing. A handlebar-mounted kill switch is encouraged.
k) Fairings or streamlining are not permitted, except for original fork-mounted number plate-cowlings. The front number plate must be parallel with the front fork angle.
l) All machines must use period-style low exhausts only. Pipes must pass below the gearshift spindle. Velocettes may use a higher, OEM racing configuration exhaust. Twins must use two separate exhaust pipes (no two-into-one exhausts).
NOTE: Classic Sixties classes are run together but scored separately.

10.5 SPORTSMAN
Sportsman classes are open to four-stroke motorcycles, up to three cylinders, built by a recognized motorcycle manufacturer for street use up to December 31, 1972. Like-design models also are permitted. Classes are 350cc, 500cc and 750cc.

10.5.1 Among the eligible Sportsman 350 motorcycles are:

BSA, all models up to 350cc
Ducati, all four-stroke models up to 350cc
Harley-Davidson, all four-stroke models up to 350cc
Honda, all four-stroke, maximum two-cylinder street models up to 350cc built prior to December 31, 1972
Norton, all street models up to 350cc
Triumph, all street models up to 350cc

10.5.2 Among the eligible Sportsman 500 motorcycles are:

BMW R50/5
BSA, all 500cc models
Ducati singles to 500cc
Honda 450 up to December 31, 1972
Moto Guzzi 500cc up to December 31, 1972
Norton, all 500cc street models
Triumph, all 500cc models

10.5.3 Among the eligible Sportsman 750 motorcycles are:

BMW R75/5
BSA, all 650cc & 750cc models
Ducati 750 round case Sport or GT (no Desmos)
Laverda SFC must compete in F750
Moto Guzzi V-7 Sport or 750 S
Norton, all 650/750 models (except short-stroke)
Triumph, all 650/750
Yamaha XS 650/750-kitted

10.5.4 REQUIREMENTS AND MODIFICATIONS FOR SPORTSMAN
a) The frame must be a pre-’73 production type (period tubing type). Frames by Trackmaster, Champion and Rickman are permitted; “Rob North” or Rickman roadrace types are not.
b) The production street engine must be used.
c) The stroke may not be changed.
d) Weslake cylinder heads, or any other than stock, are not permitted. However, it is permissible to use a twin- carb head if it will interchange with no modifications (i.e., TR6 to T120).
e) Exhaust pipes may be changed or moved for more ground clearance. TT pipes are allowed.
f) Wheel rim diameter must be at least 18 inches and cannot exceed WM3 (2.15 inches) width. BSA A65 and Triumph unit 650s in Classic Sixties 650 are restricted to 32mm carburetors, maximum one per cylinder.
g) Gearboxes may have up to five speeds.
h) 350 and 500 Sportsman machines must use drum brakes.
i) No fairings or streamlining allowed on Sportsman motorcycles.
j) Sportsman 750 machines may use one front disc brake; period-type fixed steel disc, maximum diameter 12 inches, two-piston caliper. Sportsman 750 machines may use a period-type rear drum brake or period-type rear disc with a two-piston caliper.
k) Front forks must be no larger than 38 mm unless supplied as OEM on that motorcycle. Forks with external adjusters are prohibited.
NOTE: See requirements of all roadracing motorcycles in Section 9.

10.6 NOVICE HISTORIC PRODUCTION
Novice Historic Production is open to production street machines built up to December 31, 1972, and like design. Machines must use the standard production OEM frame, swingarm, forks and handlebar mounts. Engines must be original OEM bore and stroke regardless of displacement (plus allowable overbore, as described in rule 9.7). Classes are Lightweight (four-strokes up to 500cc, 250cc two-strokes and specific 350cc two-strokes listed with an asterisk (*) below) and Heavyweight (four-strokes up to 750cc and 350-500cc two-strokes).

10.6.1 RIDER ELIGIBILITY: This class is intended for novice and non-professional veterans. At the referee’s discretion, riders who are obviously too fast for the Novice Historic Production class may be moved to a more appropriate class, such as Sportsman. Also see section 3.4.

10.6.2 Among the eligible NOVICE Historic Production Lightweight motorcycles are:

Aermacchi/Harley-Davidson 350
BMW R50
Bridgestone 350cc twin*
BSA A50, B50
Bultaco 250 Metralla
Ducati 450
Honda 350 two- and four-cylinder
Honda 400 four-cylinder
Honda 450 two-cylinder, must use OEM CV carbs or replacements no larger than 28mm
Kawasaki A1 250cc, A7 338cc twin*
Moto Guzzi 500
Suzuki T250, X-6 and T305 twin*
Triumph 500
Yamaha 250 (to RD250)

10.6.3 Among the eligible NOVICE Historic Production Heavyweight motorcycles are:

BMW R75/5
BSA, all 650 and 750 two- or three-cylinder
Ducati 750 round-case Sport or GT (no Desmos)
Honda 750 four-cylinder
Honda 500T two-cylinder
Kawasaki 500 two-stroke
Laverda SF750 (SFC must compete in Formula 750)
Moto Guzzi 750 (V7 Sport must compete in Formula 750 or Sportsman 750)
Norton, all 650/750 (except short stroke)
Suzuki 500 two-stroke
Triumph, all 650/750 two-valve head, two- or three-cylinder
Yamaha RD series 350/400 air-cooled two-stroke
Yamaha R5

10.6.4 REQUIREMENTS AND MODIFICATIONS FOR HISTORIC PRODUCTION
a) Carburetors: Must be OEM and same type (e.g., if CV, must use CV), no larger than the original OEM bore size. (Restrictors may be introduced to ensure parity of performance.)
b) EXHAUST SYSTEMS: All four-strokes must use OEM configuration exhaust systems (i.e., two-into-two, four-into-four, etc.). Effective silencers are required; no straight pipes or open megaphones. Pipes may be tucked in and mufflers raised for ground clearance. All two-strokes must use original OEM exhaust pipes as fitted on THAT motorcycle. No tuned pipes or expansion chambers. Pipes may be tucked in and mufflers raised for ground clearance.
c) BRAKES: Front and rear may be upgraded to Sportsman 750 specifications.
d) RIM SIZES: WM3 (2.15 inches) maximum front, WM4 (2.5 inches) maximum rear. Must be steel or aluminum OEM.
e) Side stands and center stands must be removed.
f) FOOTRESTS: Must remain in the original OEM location fore and aft. NO REARSETS. Footrests may be raised or modified for ground clearance.
g) Lighting equipment must be removed or totally taped over to the tech inspector’s requirements.
h) FAIRINGS AND BODYWORK: Fairings of any type are NOT allowed. Gas tank, seat and fenders must be OEM equipment or period replacements. NO modern “GSXR style” bodywork will be allowed.
i) NUMBER PLATES: 10-inch by 12-inch rectangular. White background with red numbers. Also see rule 9.5.
j) Specialty machines such as Rickman, Dunstall are not eligible.
k) Historic Production machines are NOT allowed to bump up into any other AHRMA class.
l) Except as noted above, rules 9.3, 9.4 and 9.7 apply.

10.7 BEARS®
BEARS is open to two-cylinder pushrod machines built up to December 31, 1968. Like-design models also are permitted. Among the eligible machines are:

BMW, all 1971 and earlier twins up to750cc
BSA, all 650/750 twins
Harley-Davidson KR750
Moto Guzzi, all pre-1969 twins
Norton, all 650/750 twins
Triumph, all 650/750 two-valve twins

10.7.1 All machines compete under Formula 750 rules (see 10.3.1A).

10.8 VINTAGE SUPERBIKE

10.8.1 These rules have been designed with the following intent:
a) All motorcycles competing in these classes shall be as visibly close to “production” motorcycles as possible. All eligible motorcycles shall be based on street-legal models which were available for sale in the United States and/or Canada.
b) Allow the tuner to have more influence over the performance of the motorcycle by eliminating the need for special frames, suspension systems and “state of the art” components to be developed or purchased.
c) To provide racing classes with equipment available through normal commercial channels, and in adequate quantities.
d) Provide interest to aftermarket suppliers and sponsors.
e) Provide a very distinct look and appearance from the other motorcycles competing in AHRMA events with strict bodywork requirements.

10.8.2 REQUIREMENTS AND MODIFICATIONS FOR VINTAGE SUPERBIKE
a) GENERAL
1) Model year cutoff is 1982, or like design (see definition in Section 2).
2) Engines and frames must be from the same model.
3) All street equipment must be removed (turn signals, center and side stands, mirrors, horn, helmet lock, passenger pegs, etc.). Headlight shell must be retained. Taillight and license plate bracket must be removed.
4) All motorcycles are to use three green number plates, 10 inches by 12 inches in size, with white numerals not less than 7 inches in height with a minimum of 1 inch stroke width. Standard block type numerals, without serifs, must be used. Visibility must not be blocked by rider’s foot or leg while racing. (See Section 9.5.)
5) Competitors in the Vintage Superbike classes must comply with all applicable parts of sections 1 through 9 of the AHRMA Handbook.
b) ENGINE
1) All engines must use OEM crankcases, cylinders and heads from the period 1982 and earlier.
2) Allowed displacement may be arrived at in any manner (i.e., stroker and sleeve kits are legal). Aftermarket “big block” kits are not allowed (see 1. above).
3) All round slide carbs are allowed (Keihin CR, Dell’Orto, Mikuni “smooth bore” and like design). Flat slide carbs are not allowed. Pumper carbs may be used, but the pumper mechanism must be disabled. 1025cc four-cylinders may use carburetors up to 29mm or the stock constant-velocity carburetors that were original equipment on that machine.
4) Any exhaust system design is allowed. However, all exhaust systems must be equipped with an effective silencer. Open pipes and reverse cone megaphones are not silencers. All exhaust systems must include sound attenuation material or devices. Modern canister-type silencers are not allowed. Period style exhaust systems are encouraged.
5) Liquid cooled or two-stroke engines are prohibited. (See 10.11.1d, Open Two-Stroke).
c) CHASSIS & FRAME
1) Frame must be a production model built no later than 1982 (or like design).
2) Frame modifications are allowed (bracing or gussets allowed, steering head angle may be altered, shock location changed or altered, etc.), but welds and modifications must be of the highest quality and are subject to scrutiny at tech inspection.
3) Approved period aftermarket swingarms or accurate replicas are permitted. Shock location may be changed and OEM swingarm may be reinforced, shortened or lengthened.
4) Standard shock configuration must be used, but shock(s) may be repositioned. Remote reservoir shocks are not allowed, although piggyback shocks are. BMW models may replicate factory superbikes of the period.
5) Front forks must be of OEM or aftermarket origin, with stanchions no larger than 41mm in diameter. Anti-dive and external adjusters are allowed. Forks must be conventional type (no upside down units).
6) Handlebars must be fitted to the original mounts, and must not be below the top of the fork crowns. No clubman bars or clip-ons, except when used as original equipment.
7) Any wheel from 16 inch to 19 inch is allowed. Maximum rim width: Rear 4.5 “, from 3.5”. Wheels may be wire-spoked or mag style in either alloy or magnesium. Modern alloy mag-type wheels with no more than 6 spokes are permitted. Mag type wheels with more than 6 spokes (Marchesini 10-spokes, etc.), and cut/machined aluminum wheels (Performance Machine, etc.) are not permitted. Contact the Rules & Eligibility Committee with wheel questions before purchasing wheels.
8) Only single or two-piston brake calipers are allowed. Front and rear discs, floating or rigid mount of any material except carbon fiber are allowed. “Wave” or petal-type rotors are not allowed.
9) Only treaded modern racing compound tires are allowed. Rain tires are allowed and may be “hand cut.” Tire warmers are not permitted. No slicks.
10) Airbox and toolbox may be removed or modified.
11) Fuel tank and bodywork must be as found on the same year and model of the production motorcycle on which the racer is based. Motorcycle must have original seat, which may be modified or recovered while retaining the stock seat pan. Motorcycle must have the front and rear fenders, side panels and front fairing as the original production model or accurate replicas. Fenders may be trimmed to fit tires. No tail sections may be added unless OEM on that model.
12) Only fairings that were furnished as standard equipment on the street model are allowed. Fairings must not extend below the fuel tank.
13) All motorcycles must use the OEM speedometer and tachometer housing (if so equipped). Speedometer and tachometer instruments are optional.

10.8.3 CLASSES
a) Heavyweight: Unlimited displacement twins and pushrod triples, and displacement-limited fours and sixes (see chart).
b) Middleweight: Unlimited displacement singles, with limited pushrod twins, OHC twins, pushrod triples and OHC fours (see chart).
c) Lightweight: Singles, twins and multis using performance indexes for smaller bikes (see chart).

10.8.4 All classes listed above are based upon an index of performance. If any model proves to be significantly faster than other models in its class, its performance may be restricted by limiting carburetor size, etc. If any model proves to be significantly slower than others in its class, it may be moved down to the next lower class.

10.8.5 Vintage-class motorcycles may not bump into Vintage Superbike classes.

10.9 SIDECAR
Sidecar rules are available on request from the AHRMA national office. Sidecars must meet all current AHRMA technical inspection requirements listed in Section 9, including oil retention. Drivers and passengers must meet all licensing requirements of AHRMA or another recognized sidecar-racing organization. There may be venues where sidecars are not permitted due to large entries or time constraints.

10.10 EXHIBITION
Guidelines for non-competitive exhibition or “rolling display” rides are available from the AHRMA national office.

10.11 BATTLE OF TWINS®

10.12 SOUND OF SINGLES®

10.12.1 Machine eligibility: All competition classes are intended for single-cylinder motorcycles only. All classes may be run together and scored separately as determined by the number of entries and track conditions. Classes include (section 9.8 for additional mechanical requirements):
a) Super Mono™ 2: Water-cooled single-cylinder four-stroke machines to 510cc and air-cooled single-cylinder four-stroke machines to 610cc. MZ Skorpions are permitted in Supersport spec (see rule 9.8.1); otherwise, see Super Mono.
b) Super Mono™: Unlimited displacement four-strokes.
c) SOS Two-Stroke: Two-strokes up to 550cc.
d) MOTARD: Motocross, off-road, dual-sport and motard-specific four-stroke single-cylinder machines of unlimited displacement (replaces Production Singles). Machines must meet the requirements in Section 9.8 plus the following restrictions:
1) No bodywork, fairings or slipstreaming may be added.
2) Must use flat or upswept handlebars attached to the top triple clamp. Bars must be above the top of the upper triple clamp. Dropped, clubman bars or clip-ons are not allowed.
3) Footpegs may be relocated higher, but not farther rearward, than the stock location.

10.13 SOUND OF THUNDER®

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