WATERVILLE – When Gordon Austin got a ticket in July for having loud exhaust pipes on his Harley-Davidson, he vowed to fight. This month, he made good on that promise.

On Feb. 7, Waterville District Court Judge Beth Dobson found Austin not guilty of operating a motorcycle with excessive exhaust noise — a law that was amended a week before he got his ticket.

Austin, who lives in Canaan, was one of 16 people cited for loud exhaust in Waterville under the new law and among about 160 cited statewide. Most have paid a fine. But Austin contends the law is subjective, and that many of those cited might be vindicated if they challenged their citations.

Acting as his own attorney, Austin said he told the judge that Waterville police Officer Dennis Picard had seen him riding his motorcycle around the city nearly every day last summer before ticketing him on July 23.

That was the week that Chief Joseph Massey said the department would start cracking down on loud exhaust systems.

The law previously said an exhaust system may not be modified with the intent to make it louder. The change that took effect July 12 left out the word “intent” and says the vehicle’s original muffler may not be modified to be louder.

Austin, who said he was pulled over after turning into the Maine Smoke Shop on College Avenue, said he argued that it was unfair to suddenly take issue with his exhaust noise after ignoring it the past.

“The day they’re enforcing the law they’re finding my bike loud,” he said.

Between July 12 and the end of January, police in Maine issued 157 tickets for excessive exhaust noise, according to the Maine Judicial Branch Violations Bureau in Lewiston. In the first half of 2010, there were 103 citations.

Of the people ticketed under the amended law, 17 had the charge dismissed and three — other than Austin — were found not guilty by a judge, according to the violations bureau.

“We win most of them, but we don’t win all of them,” said Kennebec County District Attorney Evert Fowle.

Fowle said he supports Massey’s effort “to keep the streets and neighborhoods down to a dull roar when it comes to exhaust noise.”

Both Fowle and Massey said they’ve heard from residents who have noticed a difference in the noise level since the department started handing out tickets. Massey said his intention is to reduce noise that disturbs outdoor diners and people sleeping in their homes — not to slap a $137 fine on people with loud exhaust systems.

“I would much rather have voluntary compliance, and I think that happened,” he said.

The chief said he’ll continue enforcing the law this summer. Austin thinks it should be rewritten first to include a maximum noise level and require officers to measure the noise before issuing a ticket.

“If I’m caught for (operating under the influence), they have to have a reading to prosecute me,” Austin said.

Massey said charging someone for loud exhaust is more like charging someone for a loud party than for driving drunk, and officers can use their common sense.