updated for 2008
2. Stock engines (block, crank, rods, stroke, pistons, cam, heads, valves, carburetor) Copper head gaskets are allowed. Plastic intake manifold allowed on OHV twins. Pushrod guide plates allowed on OHV twins. No grinding, boring, or twisting. No porting or polishing. Maximum overbore .030. No piston pop outs allowed. No turbos or pressurized intakes.
3. Engine must have been available in the brand of tractor in which it is used and must be oem stock production garden tractor engine. The brand of tractor will be based on the frame used. The tinwork, such as the fenders, hood and grill, may be switched, but swapping a motor that the oem didn't put in one of their garden tractors WILL NOT BE ALLOWED.
updated for 2008
4. Stock oem carburetors only and must NOT be altered (see rule #2). Note, using a 14 hp carburetor on a 12 hp motor is allowed due to the class being 12 to 15 hp.
5. Engine RPM must be governor controlled. Maximum rpm limit 4,250 rpm. No tolerance allowed.
6. Engines must run gasoline or diesel only; service station pumped gasoline, no additives. Ten (10) percent ethanol allowed. No E85. Electric fuel pumps are allowed.
7. Straight pipes and chrome air cleaners allowed. Exhaust must be routed to minimize dust being blown.
updated for 2008
8. Stock frames are required. No altering or axle movement will be allowed except altering engine compartment for stock replacement engine. Engine and front and rear axles must remain in stock location. Tube front axles are allowed.
9. May strengthen drive train to prevent breakage. (Reared, driveshaft, clutch, etc.) Altering gear ratios is allowed, but must have working reverse.
updated for 2008
10. Bar tires are allowed; but no professionally made pulling tires such as Cepeks, Pit Bulls, Lawntecs, etc. May sharpen front and top edge of stock bars at right angle only. No shaving back edge of bar. No adding of bars, no double cutting. No cut turf tires allowed.
11. Rear tire size: 26 x 12 x 12 maximum.
12. Aluminum wheels are allowed.
13. Clutch covers are required.
14. No starting carts allowed.