Class Name: Unlimited
1. Engines
A. Any type two-stroke cycle engine or engines, no limit to modifications.
B. Any type four-stroke cycle engine or engines, no limit to modifications.
C. Rotary engines, no limit to modifications.
2. Minimum Weight / Maximum Displacement
A. Rotary valve or Reed valve Two-Stroke Cycle Engine or Engines, 230 lbs plus one pound for each cc or fraction of a cc. Multiple engines or cylinders are permissible. 210 cc maximum total displacement.
B. Flat Head Four-Stroke Cycle Engine or Engines, 190 lbs plus one pound for every 3cc or fraction of a cc. multiple engines or cylinders are permissible. 486 cc maximum total displacement.
C. Piston Port, McCulloch or US820 (West Bend) Two-Stroke Cycle Engine or engines, 170 pounds plus one pound for every cc or fraction of a cc. Multiple engines or cylinders are permissible. 225 cc maximum total displacement.
D. Overhead
1. Single Overhead
2. Double Overhead Cam (DOHC) Four-Stroke Cycle Engine or Engines, 120 lbs plus one pound for every 1cc or fraction of a cc. Multiple engines or cylinders are permissible, 270cc maximum total displacement.
E. Overhead Valve Push Rod (OHV) Four-Stroke Cycle Engine or Engines, 220 lbs plus one pound for every 2.5cc or fraction of a cc. Multiple engines or cylinders are permissible, 500cc maximum total displacement.
F. Rotary (Wankel) engines produced for the kart racing market, 400 lbs kart and driver combined minimum weight, (this is subject to review at the end of the season). The exhaust system of all Wankel engine powered karts must be completely wrapped with heat insulating tape.
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F. Forced Induction and Nitrous Oxide. If a kart is equipped with some type of supercharger turbocharger, or nitrous oxide system, add 15 lbs for each cylinder that is served by the system.
G. Mixed Engine Type in Multiple Engine Situations. The minimum weight for the engine corresponding with the higher weight will be imposed.
H. Fuel. There are no fuel restrictions except that no illegal substance or substances may be used as fuel or as a fuel additive.
3. Calculating Displacement / Declaring Weight
A. The bore will be measured with dial calipers and the stroke with a suitable travel dial indicator.
B. The following formula will be used for calculating displacement;
BORE X BORE X STROKE X .7854 X 16.39 = CC of engine.
(This assumes that the bore and stroke were measured in inches. The 16.39 is a conversion factor from cubic inches to cubic centimeters.)
C. Always round up to the nearest whole cc when calculating minimum weight.
D. Competitors must declare their weight and display it next to their front number in such a manner that the scale person can easily see it.
E. All Competitors must have an attained age of 16 years to compete in the approved local option Unlimited Class at Caplin Speedway.