Class displacement and Configuration Limits
SuperTwins GTU
• Up to 250cc two stroke
• Up to 750cc two cylinder, four stroke (excluding Ducati 749R)
• Up to 995cc two cylinder, air cooled, two valve, four stroke
• Unlimited displacement single cylinder, four stroke

Formula 40 Class
This is an Amateur class designed for any racer 40 years of age or older, as of the day of the event. Class displacement limits are set as follows:
1) Formula 40
• Unlimited displacement and origin

Production 250 Cup Class
This is an Amateur class designed for any year Kawasaki Ninja 250 (EX250) and the 2011 Honda CBR250R produced for sale in the United States. Only the following modifications from showroom stock are permitted:
A. Bike must comply with safety standards listed in section 5.2 EXCEPT that the Production 250 Class does NOT require a steering damper. A steering damper, however, MAY be added at the riders discretion.
B. No engine modifications of any kind are permitted. Engine configuration must remain as delivered from the factory. Rebuilding or refreshing motor with OEM parts is allowed.
C. The stock airbox, air filter and intake snorkel must remain in place and connected. No modification of the airbox, air filter or intake snorkel is permitted.
D. Bodywork, windscreen, fairing stay and bodywork mounting brackets may be replaced with parts of unlimited origin. Relieving bodywork for clearance of hand and foot controls, exhaust, and frame sliders IS allowed.
E. Exhaust system, including exhaust bracket assembly, may be replaced with parts of unlimited origin.
F. Carburetor jetting consisting of main jet, pilot jet, needle and slide hole size may be changed. No other modifications to carburetor are allowed.
G. The PAIR valve may be blocked.
H. Suspension may be modified with different springs, valves, and oil. The stock rear shock body and stock fork tubes must be retained. Preload adjusters may be added to the forks. Rear ride height may be altered or adjusted. This can be done with aftermarket dog-bones.
I. Brake pads may be replaced with parts of unlimited origin, however, brake calipers and rotors must remain stock.
J. Brake lines may be replaced with parts of unlimited origin.
K. Hand and foot controls, rearsets, handlebars, and levers may be replaced with parts of unlimited origin. Brake master cylinders and throttle control must remain stock.
L. Gearing may be changed by replacement of chain and sprockets only. These parts may be replaced with parts of unlimited origin.
M. Tires must be DOT rated tires only.
N. Stock charging system must be fully connected and functional at all times.
O. Instrument cluster may be removed, and gauges may be replaced with parts of unlimited origin.
P. Only DOT approved, street legal pump gas may be used. NO race gas or performance fuel additives are allowed. At the MRA's discretion, fuel may be supplied to competitors at the prevailing market price.
Q. Parts which are not critical to bodywork or integral support may be removed, but they must be removed at the stock mounting or bolting point. Cutting of materials or frame parts is prohibited, with the exception of the kick-stand bracket which may be removed for ground clearance, and the countershaft sprocket cover may be modified or removed to accommodate "GP Shift Pattern".
R. For Kawasaki EX250’s manufactured prior to the 2008 model year, the following additional modifications beyond stock are permitted:
(1) Wheels may be replaced ONLY with OEM 2008 and up 17" Ninja 250 wheels or any generation EX500 wheels.
(2) Rear shock may be replaced ONLY with OEM 2008 and up Ninja 250 shock or any generation EX500 shock.
(3) Front end including upper and lower triple, forks, and brakes may be replaced with either 2008 and up OEM Ninja front end or any year EX500 front end.

Thunderbike
This is an Amateur class allowing superbike modifications to the specifications listed below. The following bikes are permitted to compete but must remain OEM displacement and are the only bikes allowed to be over the displacement limits: Aprilia Mille - PRE-2004 models/ Ducati - 916 and 996/ Honda - RC-51, Superhawk VTR 1000/ Triumph - Daytona 955 and Speed Triple 955/ Suzuki - SV1000, TLS and TLR. Homologation specials exceeding the class displacement limits are excluded from this class. This includes Ducati models with SPS, R, and RS designations if they displace greater than 850cc.

1. Thunderbike
• Up to 850cc two cylinder, liquid cooled, four stroke
• Up to 350cc two cylinder, liquid cooled, two stroke
• Up to 700cc three cylinder, four stroke
• Unlimited displacement two cylinder, air cooled, two valve,
• Unlimited displacement single cylinder