Regulations for On-Road Motorcycles

This page last reviewed February 19, 2004

New Standards for On-Road Motorcycles

The California Air Resources Board adopted new air emission standards for on-road motorcycles at its December 1998 Board Hearing. These new standards apply to motorcycles with engines over 280cc manufactured for the 2004 model year.



The Need for New Standards

While California continues to face the nation's toughest air quality challenges, motorcycle emission controls have fallen far behind those of cars and trucks. Motorcycles now produce up to 15 times the emissions per mile as the average new car or light-duty truck. Technologies similar to those that make new cars and trucks cleaner each year can now be used to cost effectively reduce motorcycle emissions.

Standards for on-road motorcycles will reduce emissions of new bikes by two thirds

Past Controls for On-Road Motorcycles

The first emission controls for on-road motorcycles were adopted in 1975, when the ARB set emission standards for new motorcycles manufactured for the 1978 model year. The standards applied to hydrocarbons (HC), one of the two most important contributors to smog, and carbon monoxide (CO), a toxic air pollutant. The original HC standards ranged from 5.0 grams-per-kilometer (g/km) to 14.0 g/km, depending on-engine size, and CO was set at 17.0 g/km.     

In 1984, the ARB amended these regulations to give manufacturers more flexibility to lower emissions. These new standards applied to 1988 model year and later bikes and could be met on a "corporate average" basis. The amended regulations also split larger bikes (280cc and above) into two separate categories, 280cc to 699cc, and 700cc and over. The smaller engine group (280cc - 699cc) was required to meet a 1.0 g/km HC standard, while larger engines (700cc and above) were required to meet a 1.4 g/km HC standard. The CO standard for all bikes was set at 12.0 g/km. These changes in 1984 were the last reductions applied to on-road motorcycle emissions. However, at that time the ARB directed its staff to monitor motorcycle and catalyst technology and develop lower emission standards for motorcycles once they became feasible and cost-effective.


The New Standards for On-Road Motorcycles

Technological advances made in the past 15 years to catalysts and engines can now significantly reduce motorcycle emissions. As a result, the ARB has adopted a new set of standards that will apply to 280cc and larger motorcycles starting in the 2004 model year with additional reductions required in the 2008 model year. HC and oxides of nitrogen (NOx, the other of two important smog-forming compounds) emissions are combined into a single new standard that will give manufacturers additional flexibility to lower emissions and provide motorcycles that meet consumer needs. HC plus N0x emissions is required to be reduced to 1.4 g/km for the 2004 model year and 0.8 g/km for the 2008 model year. This represents a significant reduction over the current standards while being feasible and cost effective. It is important to note that these actions will not affect motorcycles produced prior to the 2004 model year, nor require the retrofitting of existing motorcycles to meet new standards. The ARB is also discussing with manufacturers a proposal to offer an incentive plan encouraging the introduction of cleaner motorcycles prior to the 2008 model year.


Modifications to On-Road Motorcycles

Current California law does not permit modifications that increase emissions to 1978 or newer motorcycles. This would continue to apply to any motorcycles certified under the proposed new standards.


Off-Road Motorcycles

Although the new standards and regulations apply to "dual sport" motorcycles, they do not apply to off-road motorcycles for which the ARB has separate regulations.


For More Information

Please contact the Air Resources Board: (800) 242-4450 (USA only) or (800) END-SMOG (California only)

To contact us in writing: P.O. Box 2815, Sacramento, CA 95812

For Alternative Formats

(916) 322-4505 (voice), (916) 324-9531 (TDD, Sacramento area only), or (800) 700-8326 (TDD, outside the Sacramento area)