Only the modifications listed in this section are permitted. No other changes are allowed. If it doesn't say you MAY do it, then you MAY NOT.

Eligibility
Eligible Supersport machines must be sold by the manufacturer in the U.S. to the general public with full EPA and DOT approval. A list of eligible motorcycles is available from the AHRMA office. No updating or backdating of parts is allowed. The frame will determine the year and model of the motorcycle. All other parts must be from that year and model of motorcycle. Motorcycles must display a valid U.S. VIN number on the main frame.

General
The following items must be removed: Turn signals, mirrors, headlight. Taillight/brakelight must be removed or disabled. Taillight lens may be retained but must be taped over. Horn must be removed or disabled. Sidestand must be removed.

The following items may be removed: Grab rails, reflectors, rear fender, helmet lock, passenger footpegs and brackets, chain guards, radiator fan(s) and wiring.

Frame
Frames must remain stock except for the following: crash bumpers/frame sliders may be installed; frame brackets/spools may be added to permit the use of stands; aftermarket chain guards/"shark fins" may be added; frames may be polished, painted, or powdercoated, providing the VIN remains visible and readable. Subframes may be modified. Machines equipped with an OEM bolt-on subframe may replace the subframe with an OEM or aftermarket unit in steel or aluminum only.

Engine
Up to 1mm overbores are allowed only on machines with OEM cast iron cylinder liners. Only OEM pistons and rings may be used. There is no allowance for overbore on any other machines.

Cam sprockets may be modified or replaced. Cam chain tensioners may be modified or replaced.

Cylinder head, cylinder, and crankcase gasket surface may be machined for increased compression. All other surfaces of the head, cylinder, and crankcases must remain stock. Aftermarket gaskets may be used. Head and base gaskets do not have to conform to stock specifications.

Valves must remain stock. Multi-angle or radius valve jobs are permitted.

Transmission must use stock OEM parts for that model and year. Shifter return or detent springs may be replaced.

Spark plugs, clutch plates, clutch springs, and oil filters may be replaced.

Bodywork
For motorcycles produced with full fairings, replica replacement bodywork may be used. If stock bodywork includes air ducting, it may be removed. If the ducting is retained, it must be stock or exact replica replacements, and made of the same material as OEM.

Solo seat cowlings are permitted. Replacement solo tailsections are permitted providing they conform to the shape and size of the stock bodywork. OEM seats may be removed and replaced by foam padding.

Bodywork may be made of fiberglass, plastic, composite, or carbon fiber. Bodywork may be attached with non-OEM fasteners such as Dzus.

For motorcycles produced without full fairings or with less than full fairings, replica replacement bodywork from any U.S.-legal production motorcycle may be used. All other rules as detailed above apply.

Fluid retention lowers are STRONGLY recommended. (Note: The Board of Trustees has tentatively approved a rule requiring all roadrace machines to have an oil-containment system.)

Number plates may be added to the rear seat section.

Original instrument/fairing bracket may be replaced. No composite or carbon fiber brackets allowed.

OEM fuel tank must be retained and used in the OEM location. Fuel cap may be replaced.

Tires
Racing slicks, DOT-approved race tires, or non-DOT-approved rain tires may be used. No off-road or knobby tires allowed.

Suspension
Rear shock(s) may be modified or replaced. All linkage must remain stock (Suzuki TL models are allowed to use aftermarket linkage to allow for replacing the stock rotary shock with a standard-style shock.

Front fork springs may be modified or replaced. Fork oil may be changed. Fork caps may be changed. Fork internals may be modified or replaced. Fork braces may be modified or added. Triple clamps may be modified only for the purpose of adding a steering damper.

Captive wheels spacers may be added. Speedometer drive may be replaced with a spacer.

Steering dampers may be replaced or added.

Brakes
Steel braided or Kevlar brake lines may be used. Brake pads may be changed. Brake rotors may be drilled. Brake rotors may be replaced but must remain the same size as OEM. No composite or carbon fiber rotors. Brake calipers must remain stock. Brake and clutch master cylinders may be replaced. Clutch slave cylinders may be modified or replaced.

Induction
Carburetor jets and needles may be replaced. Re-sizing of air metering holes in CV carbs is allowed. Throttle slide and return springs may be replaced. Fuel lines, vent lines, and fuel filters may be replaced.

All components in the fuel injection system must remain standard except the electronic control modules, which can be modified or replaced.

OEM airbox must remain without modifications. Air filter may be replaced. Airbox drains must be sealed. Crankcase vent hose must remain routed to the airbox. Crankcase breathers may be modified or replaced.

Exhaust
Complete exhaust system may be replaced. Insulating pipe wrap is permitted.

Final Drive
Final drive sprockets and chain may be replaced. Chain size may be altered. Sprocket carrier may be replaced. Machines originally equipped with a belt final drive may change to a chain-drive system.

Miscellaneous
Rider footpegs and brackets may be modified or replaced. Shift lever, rear brake lever, and linkage may be modified or replaced.

Handlebars may be modified or replaced.

Instruments, instrument brackets, switches, and associated cables/wiring may be removed or replaced. Unused wires may be trimmed from the wiring harness, but the original OEM harness may not be replaced.

< 2004 rules proposals

Proposed 2004 Production Singles Rules

Eligibility
Street or off-road single-cylinder four-strokes that are or were available to the general public in the U.S. The Ducati SuperMono is excluded from this class.

General
All AHRMA Supersport rules shall apply to Production Singles with the following exceptions:

Bodywork
For motorcycles produced without fairings, fairings may not be added. A fluid-retention belly pan may be fitted and is STRONGLY recommended. (Note: The Board of Trustees has tentatively approved a rule requiring all roadrace machines to have an oil-containment system.)

Suspension
Rear suspension "dogbone" links may be replaced.

Tires
DOT-approved race tires with an S or higher speed rating must be used. Non-DOT-approved rain tires may be used. Slicks or cut slicks are prohibited. No off-road or knobby tires allowed.

Wheels
Wheels may be replaced. Rims may be no smaller than 16" in diameter. Wheel design, rim size, and wheel material may be changed. No carbon fiber or composite wheels allowed. Rim width should comply with the tire manufacturer's recommendations.

Brakes
Brake rotors may be replaced but can be no larger than 320mm in diameter.

< 2004 rules proposals

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