Machines that are acceptable from the period but not limited exclusively to are:

• Itom
• Tomos
• Kreidler
• Harley Davidson
• Honda C110, CR110, CA110
• Ducati
• Mondial
• Derbi
• Benelli
• Garelli
• Zundap
• Moto Morini
• Sachs

1. Engine eligibility: As a general rule all engines manufactured prior to 1970 are allowed. The gray area comes from "like or similar design" that was manufactured in a newer period. It is suggested that that any engine in question be approved by the rules committee prior to spending time and money building a race machine. Exotic works racers if original are allowed, however, merely retrofitting a more modern machine into a "works" replica will generally not be acceptable.
2. Maximum 4 speed transmission in Classic Screaming 50's.

1. Approved air-cooled engines up to 1982 allowed in Super Screaming 50's
2. YSR50 motors will be allowed granted they are iron barrel design.

1. Aprilia 50cc are allowed as stock.

1. The following rules apply to ALL machines regardless of OEM, 50cc displacement plus 5% allowable overbore.
2. Maximum 18mm carburetor size.
3. Ignition and Exhaust are your choice.
4. Frame must be of steel construction, NO moncoque or stressed skin - OEM pressed steel is OK, Steel swing arm, Twin shock suspension rear - conventional each side, Conventional telescopic or leading link suspension on front - NO upside down forks, Drum brake front and rear
5. Wheels must have a rim size of 17", 18", or 19", Maximum tire size 2.50", Minimum tire size 2.00", Conventional spoke wheels front and rear - NO cast wheels. Treaded tires only.
6. Period fairings are permitted - NO dustbin type

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