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Emission Standards for Off-Highway Motorcycles

IntroductionOff-Road Motorcycle

This web page provides a summary of the United States environmental regulations for off-highway motorcycles.  The information is provided for foreign manufacturers and importers who want to export off-highway motorcycles to the United States. The complete set of regulations is available in English at 40 CFR 1051.

The United States is very concerned about air pollution because of the health effects it causes. This includes respiratory problems, heart disease and cancer.  The U.S. Environmental Protection Agency (EPA) is responsible for writing regulations that limit the amount of air pollution from various sources, including off-highway motorcycles.

Summary of EPA Regulations

To import off-highway motorcycles into the U.S., the manufacturer must implement a series of steps to demonstrate that the motorcycles meet EPA air pollution standards.  This process includes the following steps:

  • Divide your motorcycle product line into families of vehicles that are expected to have similar emission characteristics. (For more information on selecting engine families see 40 CFR 1051.230.)
  • Obtain a certificate of conformity for each vehicle family by testing motorcycle emissions and submitting an application to EPA.  The test data must show that the motorcycles meet EPA air pollution standards for the useful life of the vehicles. You may use averaging and banking provisions to show compliance as described later in the section. Ordinarily, the manufacturer, not the importer, obtains EPA certification for imported off-highway motorcycles. However, a motorcycle importer also may apply to EPA for a certificate, on the condition that the importer assumes all the responsibilities of the manufacturer. (For more information on obtaining a certificate of conformity see 40 CFR 1051.201.)
  • Label each motorcycle with a vehicle identification number, an emission control label and a consumer information label.  If an off-highway motorcycle is not labeled, the vehicle is presumed by U.S government agencies to be uncertified. Therefore, the motorcycle may not be imported into the U.S. (For more information on labeling see 40 CFR 1051.135.)
  • Perform continual testing of production-line motorcycles.  Statistical formulas provided by EPA must be used to determine the required number of production line tests.  Tests results must be sent to EPA. (For more information on production-line testing see 40 CFR 1051.301.)
  • Maintain records including your application, engineering data and results of emission control tests.  Provide records to EPA, if requested.  (For more information on record keeping see 40 CFR 1051.350.)
  • Complete EPA Form 3520-21.  This form must be prepared by the importer for each imported nonroad or heavy-duty engine, including engines incorporated into vehicles such as non-highway motorcycles.

Emission Standards for Off-Highway Motorcycles

EPA has established emission standards for motor engine exhaust and for fuel lost through the walls of plastic fuel tanks and rubber hoses.  The emission standards for off-highway motorcycles exhaust are shown in the Table 1.  Permeations standards for recreational vehicles, including off-highway motorcycles are shown in Table 2.

Table 1. Exhaust Emission Standards for Off-Highway Motorcycles

Model Year 2007 and Later

Emission Standards (g/km)

Maximum Allowable Family Emission Limits (g/km)

HC + NOx


HC + NOx


Off-highway Motorcycle





Source: 40 CFR 1051.105
g/km = grams per kilometer
HC = hydrocarbons
NOx = oxides of nitrogen
CO = carbon monoxide

You may use the averaging and banking provisions described below to show compliance with the HC+NOX standard, but not the CO standard. If you use the averaging or banking provisions to show compliance, your Family Emission Limit for HC+NOX may not exceed 8.0 g/km for any engine family.  Off-highway motorcycles with engines that have a total displacement of 70 cc or less may be certified to standards for small recreational engines found in 40 CFR 1051.615.

Off-highway motorcycles must meet emission standards over their full useful life. For off-highway motorcycles with engines that have total displacement greater than 70 cc, the minimum useful life is 10,000 kilometers or five years, whichever comes first. For off-highway motorcycles with engines that have total displacement of 70 cc or less, the minimum useful life is 5,000 kilometers or five years, whichever comes first.

Vehicles that have adjustable parameters must meet the standards for any adjustment in the physically adjustable range. An operating parameter is not considered adjustable if you permanently seal it or if it is not normally accessible using ordinary tools. EPA may require that you set adjustable parameters to any specification within the adjustable range during any testing, including certification and production-line testing.

Table 2. Permeation Standards for Recreational Vehicles

Emission Component


Test Temperature

Fuel tank permeation

1.5 g/m2/day


Fuel hose permeation

15 g/m2/day


Source: 40 CFR 1051.110
g/m2/day = grams per square meter per test day

Permeation emissions from your vehicle's fuel tank may not exceed 1.5 grams per square-meter per day. To comply, you may generate or use emission credits under the averaging, banking, and trading (ABT) program, as described below. Permeation emissions from your vehicle's fuel lines may not exceed 15 grams per square-meter per day. Use the inside diameter of the hose to determine the surface area of the hose.

Crankcase emissions may not be discharged directly into the ambient atmosphere throughout the useful life of any off-highway motorcycle.

Averaging, Banking, and Trading for Certification

To give manufacturers flexibility in meeting the standards for off-highway motorcycles, EPA allows averaging, banking and trading:

  • Averaging applies only to manufacturers that make more than one engine family. Averaging allows a manufacturer to certify engine families based on the average emissions over all of the manufacturer’s families, in a given model year. Thus if one or more engine families are above the applicable emission standard but another engine family is certified below the same emission standard, and if the emissions averaged over all of the manufacturer’s families are at or below the level of the emission standard, the manufacturer can certify all of the families. (For more information on averaging see 40 CFR 1051.705.)
  • Banking allows an engine manufacturer to retain credits for one model year, and use them for averaging or trading in a future model year. (For more information on banking see 40 CFR 1051.710.)
  • Trading allows different engine manufacturers to exchange of emission credits among themselves.  The credits can then be used for averaging purposes, banked for future use, or traded to another engine manufacturer. Note that trading is not permitted with respect to the exhaust emission standard found in Table 1. (For more information on trading see 40 CFR 1051.715.)

Emission Warranty Requirements

You must warranty your emission control system must for at least 50 percent of the vehicle's minimum useful life in kilometers or hours of engine operation (where applicable), or at least 30 months, whichever comes first. You must warrant to the ultimate purchaser and each subsequent purchaser that the new engine, including all parts of its emission-control system, meets two conditions:

  • It is designed, built, and equipped so it conforms at the time of sale to the ultimate purchaser with the requirements of this part.
  • It is free from defects in materials and workmanship that may keep it from meeting these requirements.

This warranty is separate and apart from any other manufacturer warranty.  For more information on warranty requirements see 40 CFR 1051.120.

Importer Responsibilities

Along with the manufacturer the importer is responsible for ensuring that off-highway motorcycles imported to the United States comply with all certification standards and requirements:

  • Importers are prohibited from importing off-highway motorcycles that are not EPA-certified and labeled.  (EPA highly recommends that importers inspect the engines they intend to import to verify that they are EPA-certified and labeled.)  
  • Importers are responsible for ensuring that the off-highway motorcycle manufacturer will honor the emissions warranty.
  • The importer bears responsibility for any requirements not met by the original engine manufacturer.
  • The importer must complete EPA Declaration Form 3520-21, which requires confirmation of EPA certification or a description of the applicable exemption. Form 3520-21 must be submitted to CBP upon request along with other CBP entry documents.

For more information on importing see: http://epa.gov/otaq/imports.

More ResourcesOff-Road Motorcycle

Importing Vehicles and Engines. An EPA web page that provides various resources.

Control of Emissions from Recreational Engines and Vehicles (40 CFR 1051). The full test of the regulations for control of emissions from recreational vehicles, including off-highway motorcycles.

Final Regulatory Support Document: Control of Emissions from Unregulated Nonroad Engines (PDF) (September 2002).

Engine Emission Testing Procedure: 40 CFR Part 1065.

Snowmobiles, Dirt Bikes, and ATVs.  EPA web page provides general and technical information about land-based recreational vehicles.

Engine Certification Data. These pages provide certification data from various engine manufacturers and vehicle manufacturers for past and current model years.

EPA Form 3520-21.  This form must be prepared by the importer for each imported nonroad or heavy-duty engine, including engines incorporated into vehicles such as non-highway motorcycles. This form can be filled out electronically, except for the signature, using Adobe Acrobat Reader. Also, highlighted regulatory cites in the form are linked directly to the daily online CFR.

Enforcement Alert: EPA Enforcing Stringent Standards for All Nonroad Engines (Sept. 2006). A useful compliance assistance resource that contains information on applicable enforcement actions regarding small engines.

Enforcement Alert Many Scooters and Off-Road Motorcycle Imports Fail to Meet EPA Standards (August 2005). A useful compliance assistance resource that contains information on imported scooters and off-road motorcycles, including manufacturer and importer requirements.