Motorcycle class and manufacturer abbreviation.

(a) Motorcycles must be grouped into classes determined by separate combinations of the following parameters: (1) Engine type: (i) Gasoline—two stroke. (ii) Gasoline—four stroke. (iii) Gasoline—rotary. (iv) Other. (2) Engine displacement. (3) Engine configuration: (i) Number of cylinders. (ii) Cylinder arrangement ( i.e. , in line, opposed, etc.). (4) Exhaust system: (i) Muffler: (A) Type, (B) Location, (C) Number. (ii) Expansion chambers: (A) Location, (B) Size. (iii) Spark arrestors. (iv) Other exhaust system components.