EPA Recognizes Harmful Effects of Ethanol on Motorcycle Engines

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The U.S. Environmental Protection Agency has publicly acknowledged the dangers that ethanol may have on motorcycle engines. The EPA has approved the use of E15, a blend containing 15% ethanol and 85% gasoline in newer vehicles but not for motorcycles and ATVs. Fueling a motorcycle with E15 may void a manufacturer’s warranty.

In the write-up for a proposed new regulation from the Federal Trade Commission regarding the proper certification and labeling of ethanol-gasoline blend fuels, the EPA says ethanol may damage internal combustion engines by increasing exhaust temperatures, indirectly causing component failures.

The EPA is cited in the FTC’s document as saying: “[e]thanol impacts motor vehicles in two primary ways. First, . . . ethanol enleans the [air/fuel] ratio (increases the proportion of oxygen relative to hydrocarbons) which can lead to increased exhaust gas temperatures and potentially increase incremental deterioration of emission control hardware and performance over time, possibly causing catalyst failure. Second, ethanol can cause materials compatibility issues, which may lead to other component failures.”

The comment was made specifically in the context of E15 fuel in light-duty vehicles produced from 2001 onward, but the document says the EPA also found similar risks of damage to older vehicles, heavy-duty vehicles, motorcycles and off-road vehicles.

The FTC document also notes:


Older motor vehicles, heavy-duty gasoline engines and vehicles, motorcycles, and especially nonroad products cannot fully compensate for the change in the stoichiometric air-to-fuel ratio as ethanol concentration increases. Over time, this enleanment caused by ethanol may lead to thermal degradation of the emissions control hardware and ultimately catalyst failure. Higher ethanol concentration will exacerbate the enleanment effect in these vehicles, engines, and equipment and therefore increase the potential of thermal degradation and risk of catalyst failure. In addition to enleanment, ethanol can cause materials compatibility issues which may lead to other component failure and ultimately exhaust and/or evaporative emission increases… For older motor vehicles, heavy-duty gasoline engines and vehicles, motorcycles, and nonroad products, the potential for materials compatibility issues increases with higher ethanol concentration.


The comments from the EPA support a long-held stance from the American Motorcyclist Association that E15 fuel harm motorcycles and ATVs. The AMA is concerned about the growing presence of E15 in gas pumps and the potential risk of motorcyclists unknowingly filling their tanks with the fuel blend and damaging their vehicles.

“The American Motorcyclist Association has fought the distribution of E15 fuel blends in an effort to protect motorcycle and all-terrain vehicles from the damage that ethanol causes,” says Wayne Allard, AMA vice president for government relations. “Now the EPA acknowledges that ethanol itself is harmful to emissions hardware and other components on all motor vehicles. It is time for the federal government to pause, take a hard look at this product and change its entire approach to ethanol in fuels.”

So far, the EPA has been onside with the AMA’s concerns with E15, enacting measures to make E10 (10% ethanol) its standard test fuel and refusing to grant a waiver that would make E15 fuel more available in gas stations in warmer months.

[Source: AMA]

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