California: Motorcycles: Emissions


The California Air Resources Board sets standards for both exhaust and evaporative emissions from motorcycles, specifically setting parameters for HC, NOx, and CO. Emissions are calculated using a “corporate average” formula and utilize test procedures from the US EPA.

Standard type
Conventional pollutant emission limits
Regulating Body
California Air Resources Board (CARB)
Current Standard
Title 13, CCR §1958 (exhaust) and §1976 (evaporative)
Motorcycles or engines manufactured on or after 1 January 1978


CARB administers a program for reducing emissions from highway motorcycles. Authority for controlling emissions from highway motorcycles is established in sections 1958 (exhaust) and 1976 (evaporative), title 13, California Code of Regulations (CCR). The California exhaust emission test procedures are adopted from the US Environmental Protection Agency’s (EPA’s) exhaust test procedures in title 40, Code of Federal Regulations, Part 86, subpart E and subpart F.

The original (1975) regulations set hydrocarbon (HC) and carbon monoxide standards for all motorcycles with engine displacements of at least 50 cubic centimeters (cc). The 1998 amendments added control of oxides of nitrogen (NOx) to the regulations for the larger, Class 3 motorcycles (280 cc or greater). They set a Tier I standard of 1.4 grams per kilometer (g/km) HC+NOx beginning with 2004 models and a Tier II standard of 0.8 g/km HC+NOx beginning in 2008 for major manufacturers. The standards include corporate averaging provisions. For small volume manufacturers, the Tier I requirement begins with the 2008 model year; there is no Tier II standard. Small volume manufacturers were defined in the final regulations as manufacturers with annual California sales of no more than 300 motorcycles.

A 2006 Review of the 1998 Amendments to the California On-Road Motorcycle Regulations assessed the progress made by manufacturers to meet 2004 and 2008 on-road motorcycle emission requirements.

Technical Standards


This regulation is applicable to motorcycles, motorcycle engines, and the manufacturers of either motorcycles or motorcycle engines produced on or after 1 January 1978.

As defined in California Health & Safety Code, Section 39041 and in California Vehicle Code, Section 400, a motorcycle is:

(a) A motor vehicle having a seat or saddle for the use of the rider, designed to travel on not more than three wheels in contact with the ground.
(b) A motor vehicle that has four wheels in contact with the ground, two of which are a functional part of a sidecar, is a motorcycle if the vehicle otherwise comes within the definition of subdivision (a).
(c) A farm tractor is not a motorcycle.
(d) A three-wheeled motor vehicle that otherwise meets the requirements of subdivision (a), has a partially or completely enclosed seating area for the driver and passenger, is used by local public agencies for the enforcement of parking control provisions, and is operated at slow speeds on public streets, is not a motorcycle. However, a motor vehicle described in this subdivision shall comply with the applicable sections of this code imposing equipment installation requirements on motorcycles.

Motorcycles and motorcycle engines are excluded if:

(1) The engine displacement is less than 50cc, or

(2) An 80 kg (176 lb) driver cannot

(A) start from a dead stop using only the engine, or
(B) exceed a maximum speed of 40 km/hr (24.9 mph) on a level paved surface.

Emission Standards

California regulates HC, NOx, and CO emissions from motorcycles. The useful life of 279 cc motorcycles is 5 yr/30,000 km.

Exhaust Emission Standards
Model Year Engine Displacement
1978 – 1979 50 < cc < 170 5.0 (HC only) 17
1978 – 1979 170 ≤ cc < 750 5.0+0.0155(D-170) (HC only) 17
1978 – 1979 ≤ 750 14 (HC only) 17
1980 – 1981 All (≤50 cc) 5.0 (HC only) 17
1982 and subsequent 50 < cc ≤ 279 1.0 (HC only) 12
1982 – 1985 (manufactured prior to March 1, 1985) ≤ 280 2.5 (HC only) 12
1985 – 1987 (manufactured after February 28, 1985) ≤ 280 1.4 (HC only)* 12
1988 – 2003 280 < cc ≤ 699 1.0 (HC only)* 12
1988 – 2003 ≤ 700 1.4 (HC only)* 12
2004 – 2007 ≤280 1.4 * 12
2008 and subsequent ≤280 0.8 * 12
† D = engine displacement of motorcycles in cubic centimeters.
‡ Compliance with a standard to be applied as a “corporate average.” See below.
* Small manufacturers are currently exempt from Tier 2

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