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12 HP LIGHT MODIFIED PRO TIRES

  1. Single cylinder 12 HP engines and under.

  2. 4,000 RPM limit, regardless of flywheel type.

  3. 1,050 pounds weight limit.

  4. All tractors must be stock in appearance. Officials must approve alterations.

  5. All engines must have OEM dimensions and specifications noted in these rules.

  6. Stock Block - can be sleeved - must maintain stock bore no more than .030 over.

  7. Stock head.

  8. Stock crankshaft stroke must be maintained. Steel cranks allowed.

  9. Stock valves required.

  10. After market camshafts permitted..330" max lift at zero lash.

  11. Head gasket must be a composition gasket – no copper gaskets.

  12. Stock carburetor required – venturi to be no more than 1.200" diameter.

  13. Choke can be removed.

  14. No intake standoffs allowed – 1 inch spacer maximum.

  15. No porting or polishing of intake and exhaust areas allowed. Deburring in these areas is permitted.

  16. Exhaust for all tractors must discharge upwards or towards the rear of the tractor - not out to the side, unless running stock muffler (discretion of officials).

  17. All clutch assemblies must be covered 180 degrees on topside. If you have belts, they must have a safety shield.

  18. 13" hitch height maximum.

  19. 26x 12x 12 tire size maximum (can be sharpened).

  20. Pump gas or racing gas allowed, no alcohol or nitro.

  21. No electric fuel pumps.

  22. Canister type coil, no high performance alterations (discretion of officials).

  23. Water cooled engines and overhead valves permitted.

  24. 60" Wheelbase max.

  25. Dead Man throttle (must return to idle automatic).

  26. Must have working kill switch with 2 inch ring.

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