CFR > Title 40 - Protection of Environment > CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY > SUBCHAPTER G—NOISE ABATEMENT PROGRAMS (Parts 201–211) > PART 205—TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS > SUBPART D—Motorcycles (§205.150 to §205.163) > 205.155—Motorcycle class and manufacturer abbreviation.

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.