ShareThisDespite a recession that has seen a drop in new car and truck registrations, motorcycle registrations in California boomed by 6.6 percent in 2008.
The state is home to 841,081 registered motorcycles, along with a riding community estimated to be well over 1 million people.
But although motorcycles make up only 3.8 percent of California registered vehicles, they create 8.1 percent of all vehicle emissions in the state, according to the California Air Resources Board.
That's because mile for mile, the average motorcycle emits more pollution than cars do, said John Swanton, a specialist at the state agency responsible for air quality regulation.
As the popularity of motorcycles grows, so has awareness of their role in air pollution. A proposal to require motorcycles to pass every-other-year smog checks, as cars and trucks are required to do, stalled in the California Legislature this year after motorcycle groups opposed it.
Sen. Fran Pavley, D-Agoura Hills, is continuing to work on the bill and might amend it to drop the smog check requirement in favor of directly targeting the issue of catalytic-converter removal. Motorcyclists frequently customize their exhaust pipes -- often by removing factory-installed catalytic converters that remove pollutants from exhaust -- to make their bikes louder and faster.
State law prohibits modifications that increase emissions but doesn't specifically outlaw removing catalytic converters.
The difficulty in outlawing removals is enforcement. A smog check is one way the state could determine if the parts were removed. Pavley is exploring other ways to enforce the law.
The issue has created a classic tug-of-war between riders, who say new regulations would limit personal freedom, and environmentalists arguing for protection of public health.
Southern California is especially popular for motorcyclists, with famous bike roads in the Santa Monica Mountains, Ojai Valley and along the Pacific Coast Highway.
Pete Christensen, a rider and service manager at a Cal Coast Motorsports in Ventura, said it's no surprise motorcycles are popular in the state.
"California is definitely the best place for motorcyclists, not just because of the weather, but because of the roads we have here to ride," Christensen said. "It is something you can do that's a lot of fun."
Motorcycles also have unmatched fuel economy -- some can get more than 60 miles per gallon. Their engines often work harder and faster than car engines, creating more energy with less fuel. Such engine characteristics, however, produce more smog-forming hydrocarbons and nitrogen oxides.
"Many motorcycles have high-performance, high-compression engines, and those are conditions that are ideal for creating nitrogen oxides," Swanton said.
Swanton said a popular motorcycle such as the Suzuki GSX-R 600 creates about 14 times more pollution per mile than a Toyota Camry.
California already has the strictest vehicle emissions laws in the nation, including those governing motorcycles sold in the state. To meet the standards, 87 percent of motorcycles sold in California in 2008 were equipped with catalytic converters.
Riders, however, say modifying and customizing motorcycles is an integral part of owning one.
"Whether it's just a piece of chrome on it or rebuilding the engine to make it real, real strong, that's part of our culture," said Tom Cass, a lifelong rider and president of Simi Valley ABATE, a motorcycle rights group. "You want your bike to be your own bike, not what Joe Blow's got. You want to be able to stand out."
One of the most popular modifications is a custom exhaust system. Sacramento motorcycle shop owner Darrin Woll describes custom exhausts as "one of the first purchases" riders will make.
Derek Eshlemann, a Westlake Village resident and sport bike rider, said there are three reasons why motorcyclists modify exhaust systems. "First, I would say sound. Then I would say performance and looks," Eshlemann said. "When you add it for sound, I think it has a big effect on the rider's mentality when they're riding."
Motorcycles in California are sold with relatively quiet exhaust systems. If certain components are removed, the raw sound of fuel exploding in the engine is unleashed.
Cass said some emission controls also hinder a bike's engine. "In 1995, Harley-Davidson started installing catalytic converters on their exhaust pipes, and it really takes away a lot of the performance of the bike by doing that." Cass said.
According to state regulators, modification can cause emissions to increase tenfold.
But Cass said motorcycles are not big contributors to smog relative to other vehicles. Motorcycles are used mainly for recreation, and often do not see daily use. Although they represent nearly 4 percent of vehicles, they only account for 0.8 percent of vehicle miles traveled.
(Evan Sherwood is a reporter for the Ventura County Star in California.)
