1.   Single cylinder four cycle flathead engines only and must be Kohler, Wisconsin, Tecumseh or Briggs.

2.   Engine blocks must be OEM stock factory productions with factory deck height. No reproductions or Woolam or J2 blocks allowed.

3.   Stock Head bolt pattern, location and size. Stock head gasket must fit over studs or bolts.

4.   Stock stroke only with a maximum 32 cubic inch displacement (allows for .030" overbore of 14 hp block).

5.   Engines must use stock lift cams and stock diameter valves.

6.   Maximum carburetor venturi size 1.00", no air entering after 1.00" restriction. Venturi must be round in shape. Note, this is referring to the venturi, not the throttle or choke bore.

7.   Carburetor must be a stock OEM Kohler-type with no spacers allowed. No recast carbs allowed. No turbos or pressurized intakes.

8.   No reverse port engines allowed, carburetor must go to the original stock intake port.

9.   Stock or stock appearing heads required. No Billet heads allowed.

10.   Porting and polishing allowed

11.   No rpm limit but steel flywheels are REQUIRED.

12.   No starter-generators allowed. Must use ring gear starter or starter-cart.

13.   No external welding except for crankcase area of the block for repair. But no other external modifications allowed.

14.   Engines must run gasoline, E10, E85 only; service station pumped gasoline, no additives. Racing gas is allowed.

15.   Straight pipes and chrome air cleaners allowed.

16.   Must run a factory appearing hood and grill, use garden tractor rear-ends and stock garden tractor frames that are factory length with a maximum wheelbase length of 52 inches.

17.   May strengthen drive train to prevent breakage. (Reared, driveshaft, clutch, etc.) Altering gear ratios is allowed.

18.   Bar tires are allowed; but no professionally made pulling tires such as Cepeks, Pit Bulls, Lawntecs, etc. Tires must be ag type bars. No double cutting of tires, no adding bars, but can single cut the bars in any fashion. No cut turf tires allowed.

19.   Rear tire size: 26 x 12 x 12 maximum.

20.   Aluminum wheels are allowed.

21.   Clutch covers and flywheel shields are required. Minimum thickness 1/8 inch steel or 3/16 inch aluminum.

22.   Driveshafts must have a support bearing in the center or driveshaft loop.

23.   Engines must have a scatter shield opposite the cam side of the motor. Minimum thickness 1/8 inch steel or 3/16 inch aluminum. It must cover the full height and width of block and be attached in a secure manner to the frame and head.

24.   Engines must have a hold down restraint installed to prevent the cylinder and head from separating from the block.

25.   Bumper bars are required. These are a vertical bar at least 6" long mounted on rear most part of wheelie bars. Vertical bumper bar must be even with or behind back face of wheelie wheel or skid.

26.   Tractors must have WORKING kill switch fastened to the rear of the tractor in such a way that it does NOT interfere with weights or sled hitching device. The connector must be fitted with a ring with a minimum of 1.5" inside diameter.

27.   A minimum 1 1/2 pound dry chemical working fire extinguisher or equivalent. A gauge on the fire extinguisher is required or an inspection and recharge tag not more than two years old. They can either be dry chemical or CO/2-type extinguishers.

28.   Tractors must have deadman throttle with return springs on the pedal and the carburetor.

29.   Drivers must wear helmets that meet minimum Snell 95 requirements. No football, baseball or toy helmets.

30.   Drivers must wear long pants and boots. No sandals or open toes.