The New EPA Motorcycle Emissions


The EPA has recently published its Notice of Proposed Rulemaking (NPR) in the Federal Register to establish new low engine emissions standards for highway motorcycles. This is a follow-up to the recently approved off-highway vehicle emissions standards that spelled the demise of 2-stroke engined motorcycles and ATVs.

Motorcycle emission standards were first established in 1978 by the EPA and have remained unchanged since the 1980 model year. Those standards are 5 grams per kilometer hydrocarbon and 12 grams per kilometer carbon monoxide (5 g/km HC and 12 g/km CO). Only one state, California, received permission from the EPA to set its own lower standard because of its unique smog problems and, in several stages, reduced its motorcycle emission standard to 1.0 g/km for 50-699cc and 1,4 g/km for 700cc and above motorcycles. The current California emissions standard is therefore 3 1/2 to 5 times cleaner than the Federal one.

Additionally, in 1988, the California Air Resources Board (CARB) passed new standards that will further impact motorcycles after 2004. New motorcycles over 280cc, sold in Calif., after 2004 must certify to no more than 1.4 g/km HC PLUS oxides of nitrogen (Nox), and after 2008, must meet a 0.8 g/km HC + Nox standard.

Manufacturers expect to meet the Tier 1 (or 2004) standards with little difficulty because engine design technology and manufacturing proficiencies are advancing rapidly. Most of the popular motorcycle models, sold all over the U.S., already meet the Calif., 1.4 g/km HC for manufacturing and distribution efficiencies so that two or more models don’t have to be produced for different parts of the country.

It should be mentioned, however, that a number of performance models and most water-cooled V-twins barely meet the current 1.4 g/km Calif., standard and, even if they do, they perform poorly without questionably legal modifications.

In fact, for over two decades, dealers, shops and even owners have been prohibited by federal and state law from, actions that remove or disable emission control devices or cause the emissions to exceed the control standards.

The real problem exists with the Tier 2 standard for 2008. To meet the 0.8 HC+Nox standard, secondary air-injection, fuel-injection and catalytic converters will have to be employed for most, if not all motorcycle models. The 2008 standard was so controversial that CARB must hold a technology progress review in 2006 to evaluate the motorcycle manufacturer’s progress in meeting the 2008 standard.



Simply, the EPA is proposing to adopt the above California Standards, but delay the implementation for two years, until from 2004 to 2006 (Phase 1) and from 2008 to 2010 (Phase 2). respectively. This will give the EPA adequate time to delay or amend their rule if CARB recognizes that their standard is too severe and can not be met by the motorcycle manufacturers.

The conventional wisdom is that it will be too severe, particularly Phase 2, and the cost will ruin motorcycling and will not reduce pollution.