(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) × 3 × 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.
Title 40 published on 2013-07-01
The following are only the Rules published in the Federal Register after the published date of Title 40.
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This is a list of United States Code sections, Statutes at Large, Public Laws, and Presidential Documents, which provide rulemaking authority for this CFR Part.