[Code of Federal Regulations] [Title 40, Volume 22] [Revised as of July 1, 2003] From the U.S. Government Printing Office via GPO Access [CITE: 40CFR205.155] [Page 130] TITLE 40--PROTECTION OF ENVIRONMENT CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PART 205--TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS--Table of Contents Subpart D--Motorcycles Sec. 205.155 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.