Pro Stock Rules
To read more about the rules for Pro Stock Harley read the Pro Stock Harley rules and more at AHDRA, which stand for the All Harley Drag Racing Association.
- ENGINE
Engine: Will consist of 45-degree XL or 45-degree FX based engines up to 122 cu.i. (2000 c.c. maximum). Must use conventional fork and knife connecting rod set-up. Any engine modifications are legal. Engines must be carbureted. Pushrod aftermarket heads are legal. Lateral valve stem angle must be zero degrees and minimum longitudinal valve stem angle is 18 degrees as measured parallel from a vertical line centered in the respective cylinder bore. All engines must be naturally aspirated and all air and fuel must be delivered through one or two single throat carburetors or one dual throat carburetor. Air induction is limited to concentric, continuous reducing diameter velocity stack(s) with a maximum opening area of 20 square inches each. No cups or scoops are allowed. A single air dam may be mounted to a carburetor mounted 1/8 inch backing plate. The air dam may not exceed 2 and ½ inches in height and may not extend forward beyond the centerline of the rear carburetor. CPR systems are legal, but they must not have any hoses connected to intake manifold. Crankcase vent tube must be routed to catch can or have a non-spill breather system on motorcycle.
Fuel: VP Racing Fuels C-25 is the specified fuel. No Fuel additives and /or combustible oil additives are allowed. Dielectric constant, as per AHDRA testing meter, must match baseline reading of specified fuel. Fuel must match color of specified fuel. Fuel must match AHDRA generated graphs in random Gas Chromatography analysis of specified fuel.
- DRIVE TRAIN
Chain Guard: Must have chain or belt guard for primary and secondary drives.
Transmission: Must have XL or FX based 4 or 5 speed transmissions. Belt drives are legal. Rear wheel drives may consist of any ratios. Air shifters and electric shifting devices must be manually operated. No automatic transmissions. No variable speed belt drives. No slipper clutches allowed. Clutch must be manually operated by rider’s hand.
- SUSPENSION AND BRAKES
Brakes: Front and rear mandatory (disc or drum).
Controls: Handlebar controls must be located in safe, workable position. Minimum handlebar width is 20 inches. Foot pegs and foot controls must be located in safe, workable position and must be mounted in a safe, craftsman like manner. Foot pegs are recommended to be 12 inches in front of rear axle. All controls must meet or exceed OEM equipment standards. Snap-back throttle return mandatory.
Suspension: Front suspension minimum size 30 mm and minimum travel of 2 inches. Fork stops required. Rear suspension not necessary if running wheelie bars.
- FRAME
Frame: Stock production, aftermarket and specialized racing frames any style chrome moly or steel frames allowed.
Ballast: Permitted. Ballast must be in weight box or securely bolted to frame by a minimum of one 3/8-inch bolt per 5 lbs.
Ground Clearance: Minimum of 2 inches with rider on motorcycle and 10 p.s.i. in rear tire (includes exhaust and kick stand).
Wheel Base: 70 inches maximum (measure from center to center of front and rear axles), includes chain adjustment.
Wheelie Bars: Wheelie bars are required. Maximum length from center of front axle to center of wheelie bar axle cannot exceed 130 inches.
- WHEELS AND TIRES
Tires: Must be V rated or specified for racing use by manufacturer. Maximum rear tire width 9.5 inches. Minimum front tire width 3 inches. Tire width is actual tread or friction surface width.
Wheels: Rear wheel minimum 15 inch, maximum 18 inch.
- BODY
Body: All motorcycles must have front and rear fender with gas tank or shell to resemble street motorcycle appearance. Must be mounted and constructed in a safe, craftsman like manner. Rear fender must cover the width of the rear tire and extend beyond the vertical centerline of the rear axle.
Fairing: Allowed.
Seat: Stock OEM or seat with a step to prevent the rider from sliding backwards.
- ELECTRICAL
Ignition: Any ignition system is allowed.
Charging System: Not necessary.
Starting System: Must be electric, kick and external starter. Battery top covers are required. No rollers. No push starts. No dry hops in pits.
Control Switches: Must be mounted and constructed in a safe, craftsman-like manner. Must have an emergency kill switch.
Computers: Only data gathering computers are allowed.
Lights: Not necessary.
- RIDER
Credentials: Valid AHDRA 7.90 competitor license.
Helmet: Full coverage helmets only! Must be Snell-2000 approved. Eye protection required.
Protective Clothing: Full finger leather gloves with knuckle armor and palm reinforcement, one piece or full circumference zippered leather suit with knee, elbow and shoulder armor or reinforcement, spine/back protector and above the ankle leather boots with toe area reinforcement are required.
Race Team Clothing: All team crewman that help start, assist in burnout and stage race motorcycle must wear a uniform shirt that relates to their specific team.
- TECH
Tech: All motorcycles must be teched in before practice. Motorcycle, rider and his protective gear must be present at tech area. Tech official will have final say on any unclear rule or equipment.
Additional Resources
AHDRA at http://www.ahdra.com/index.html
Harley drag race histor and program details;
Harley Drag Race Program