Period III Middleweight Supervintage 

Middleweight Supervintage is limited to race-prepared motorcycles that were originally sold for street use, all frames must specifically have been sold for street use, with a maximum model year of 1975 or like models, two- or four-stroke. Dry clutches, all alloy cylinders, and power exhaust valves prohibited:

  •     Up to 400cc single cylinder 2-stroke
  •     Up to 380cc-twin cylinder 2-stroke
  •     Up to 400cc triple cylinder 2-stroke
  •     Up to 600cc single cylinder 4-stroke
  •     Up to 650cc-pushrod twin cylinder 4-stroke
  •     Up to 550cc single OHC four cylinder 4-stroke
Maximum displacements above do not include permissible overbores of 5% over class limit.

The following machines are permitted regardless of model year:

  •       Honda single OHC four cylinder CB400, CB500, CB550 thru 1978 model year
  •       Kawasaki S2 350, S3 400
  •       Suzuki GT380
  •       Yamaha RD350
NOTE: above "excepted" machines are still subject to general Supervintage rules set forth below, irrespective of original equipment.

NOTE:  Period III Middleweight Supervintage legal machines may NOT bump to Period II. 

Rules applicable to III Supervintage Class:
i. Engine: No pressurized induction. Internal updating permissible; external appearance should remain same.
ii. Gearbox: Internal updating permissible; external appearance should remain same.
iii. Wheels: Wire-spoked wheels, minimum 17 inch diameter, maximum width 2.5 inches (WM-4) front, 3.0 inches (WM-5) rear.
iv. Tires: maximum width of 140mm (as stamped by manufacturer on tire). Treaded tires only: no slicks, or slicks treaded after manufacture.
v     Brakes: period type and make required; discs allowed - period calipers ONLY.
vi. Maximum fork tube diameter 38mm unless machine originally equipped ex-factory with larger units.
vii. Swingarms must be 2-sided, of period design and materials, and have a shock absorber located on each side without secondary linkage (OEM excepted; e.g., Vincent and NSU).
viii. Bodywork must be of a design and appearance actually used in the applicable period.
vii. Carburetors: Round slide or Sand cast "tickler" type CR carburetors, or Die-cast CR carburetors allowed in Period III.

Table of Contents (click on any item to view that page)
Names and Addresses
Class Overview
Bumping
Rule Changes
Championship Points
General Rules
Early Vintage & Pre '65
Screaming 50's
Grand Prix (Period I)
Supervintage (Period II)
Middleweight (Period III)
Period IV
Formula RD
Formula CB350
Sidecars
American Twins

Last Updated: 2/25/06