AUGUSTA – A legislative committee endorsed new inspection regulations for motorcycles Friday in an attempt to quiet their roar.

If the full Legislature agrees with the Transportation Committee, motorcyclists may have to display inspection stickers on their bikes as soon as this summer, and abide by new inspection rules banning noisy after-market parts.

Sen. Nancy Sullivan, D-Biddeford, the sponsor of L.D. 1675, calls reducing motorcycle noise a ”public health issue.”

At an earlier hearing, she said 38 percent of motorcycles in the state are not inspected.

Inspections under the legislation would require motorcycles to have stock or factory mufflers, not after-market models that amplify the noise of the engine, said Sen. Dennis Damon, D-Trenton, co-chairman of the Transportation Committee.

Motorcycle advocates said the bill amounts to unnecessary legislation that would not solve the problem.

”You can have your inspection done, go home and put on straight pipes and still ride,” said Joshua Herndon of the Maine Motorcyclist Political Action Committee and United Bikers of Maine.

”There is a problem with excessive noise, but it could be dealt with under existing law.”

Herndon also said that state inspection requirements do not address riders from outside Maine.

In addition to the inspections, the bill endorsed by the committee calls for a study group to meet this summer and report in January 2011 about how to define and police excessive motorcycle noise.

The regulation could include roadside enforcement, with police using decibel monitors.

Motorcycle advocates expressed concern that the requirement to display inspection stickers on bikes’ suspension forks would damage expensive chrome or painted finishes.

”There’s a lot of difference between scraping an inspection off glass and a piece of chrome,” Eric Fuller, chairman of the Maine Motorcyclist Political Action Committee, told Sullivan.

Motorcyclists are now required to carry, but not display, inspection certificates.

”Because you can’t see it,” said Damon, ”the police have been a little reluctant to stop motorcycles based just on noise.”

Three of the 10 committee members who voted Friday preferred that the stickers be attached to the rear license plate.

When the committee voted, however, it was not aware that non-adhesive motorcycle inspection certificates for next year have already been printed and delivered to the state.

Damon said that could postpone implementation of the sticker requirement, because of the added cost of printing new stickers.