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INTRODUCTION:
The AMERICAN TWINS class is a spec type class, for relatively stock XL883 Evolution Sportster based Harley Davidson motorcycles built between 1986 to the present.
1) American Twins rules are designed to be simple and easy to enforce.
2) American Twin rules are designed to keep racing close, competitive, reliable, track safe and relatively inexpensive.
All general safety rules and regulations of the United States Classic Racing Association apply to the American Twins Class.
The following lists some of the general applicable rules pertaining USCRA racing motorcycles. This list is a brief guide. In order to compete in USCRA events, it is the rider's responsibility to insure that all rules and regulations for USCRA machine preparation and eligibility as per the rulebook are followed.
1. Headlights, tail lights, horns, mirrors, side stands, etc., must be removed
2. A suitable 3-quart capacity belly pan must be installed as per USCRA requirements.
3. Gas caps must be secured by either duct tape or safety wire.
4. The entire motorcycle must be properly safety wired as per USCRA rules
5. A proper oil catch bottle must be attached.
6. Oil filters must be hose clamped, and then properly safety wired securely to either the frame or
the engine.
7.All front fender rivets must be drilled out and replaced with nut secured bolts.
RULES UNIQUE TO THE AMERICAN TWINS CLASS
NO ENGINE MODIFICATIONS WILL BE ALLOWED EXCEPT AS NOTED BELOW.
Any OEM Harley Davidson parts book listed XL883 part, from any year XL883, may be used. (Example: An OEM carburetor from a 2005 XL883 may be used on a 1986 XL883 race bike.) This practice is known as "Parts Interchange". OEM ignition boxes must be used, thus limiting max RPM to 6500. Electric starters may NOT be removed and must be fully operational.
ALOWABLE MODIFICATIONS: (If its not listed below, it must remain stock.
When in doubt, check it out with the rules committee. The USCRA reserves the right to make additional rules clarifications and changes as necessary to maintain machine safety and parity)
1. VALVES and SEATS may be re-cut.
2. Exhaust systems may be changed or modified (Systems must meet current noise restrictions for NHIS.)
3. Any carburetor jetting (including commercial jet kits) and air cleaners may be used.
4. Racing handlebars or clip-on handlebars may be used.
5. Treaded tires only. (Wheels must remain OEM)
6. Sprockets and chains may replace belt drive systems.
7. Sprocket spacers may be used if needed for tire clearance.
8. Any brake pads, brake lines, and brake fluid may be used.
9. OEM disks may be drilled for cooling.
10. A second front disk may be added by using OEM parts only.
11. OEM foot pegs may be altered or NON-OEM REAR SET ASSEMBLIES MAY BE ADDED.
12. Seats must be OEM based. Seats may be cut down or re-shaped.
13. Fork braces may be added.
14. Non-OEM Fork springs / oils may be added or changed.
15. Rear shocks, including length may be changed. (Mounting points must remain stock.)
16. Non-OEM oil filters and lubricants may be used
17. PORTING OF THE INLET TRACT MAY NOT BE MODIFIED, ALTERED OR CLEANED UP.
PLEASE NOTE: TO INSURE MACHINE ELIGIBILITY ON ANY AMERICAN TWINS ENTERED MACHINE, THE USCRA MAY AT ANY TIME REQUIRE AN ENTRANT TO DEMONSTRATE PISTON AND CAM COMPLIENCE.
Table of Contents (click on any item to view that page)
UPDATED 2005 / 2006 RULEBOOK!
Names and Addresses
Class Overview
Bumping
Championship Points
General Rules
Formula CB350
American Twins
Endurance Racing
