(a)(1) Engine displacement shall be calculated using nominal engine values and rounded to the nearest whole cubic centimetre, in accordance with ASTM E 29-67.
(1) Engine displacement shall be calculated using nominal engine values and rounded to the nearest whole cubic centimetre, in accordance with ASTM E 29-67.
(2) For rotary engines, displacement means the maximum volume of a combustion chamber between two rotor tip seals minus the minimum volume of that combustion chamber between those two rotor tip seals times three times the number of rotors. cc=(max. chamber volume - min. chamber volume) x 3 x no. of rotors
(b) Motorcycles will be divided into classes based on engine displacement.
(1) Class I--50 to 169 cc (3.1 to 10.4 cu. in.).
(2) Class II--170 to 279 cc (10.4 to 17.1 cu. in.).
(3) Class III--280 cc and over (17.1 cu. in. and over).
(c) At the manufacturer's option, a vehicle described in an application for certification may be placed in a higher class (larger displacement). All procedures for the higher class must then be complied with, compliance with emission standards will be determined on the basis of engine displacement.