Starting in January, moped owners in Hawaii will need to pay for annual registration and inspections, plus get plates for their vehicles — similar to the state’s existing requirements for cars, trucks and motorcycles.

House Bill 1753, which Gov. David Ige signed into law Tuesday, follows a recent grass-roots effort to curb noise from illegally modified mopeds in Honolulu.

Moped owners across the state will have to pay a yearly $27 registration fee, which was reduced from the proposed $50 fee that state lawmakers had considered during their session earlier this year. Currently, moped owners in Honolulu pay a one-time registration fee of $15 — the same as for a new bicycle.

The new moped inspection fee on Oahu will likely be the same as for motorcycles — $13.24 — although that hasn’t been confirmed yet, state and county officials said.

Residents across Oahu said the situation involving illegally modified mopeds has gotten out of hand. Some 15 of the island’s 33 active neighborhood boards passed resolutions supporting the state legislation to take action against the vehicles’ noise, according to Tim Streitz, a McCully-Moiliili Neighborhood Board member who helped lead the effort to pass the legislation.

“This really shows off the power of the neighborhood board system. Nothing like this has ever happened before,” said Bob Kern, a Manoa resident who says he’s been plagued by the issue for years. “There’s so much noise in this city, and it’s a recognition that noise is a problem.”

Kern and others said they can hear the difference in decibels between a moped that’s been modified versus an unaltered one that’s just loud. The noise comes at all hours of the day, Kern said. He and others said mopeds often startle them awake late at night and in the early morning hours.

The culprit, according to one prominent moped dealer on Oahu, is a subculture of moped enthusiasts in Hawaii that values older, so-called “two-stroke”-engine mopeds because they perform dramatically better (and louder) when modified.

The law’s new safety check program will allow police to send mopeds back for re-inspection if they suspect it’s been illegally modified since its previous check. Moped owners and drivers who don’t have current inspection certificates face a fine of up to $100 under the new law.

“It should help,” Honolulu Police Department Maj. Darren Izumo said after the law’s signing ceremony at the state Capitol. “Now that they have to be registered like motor vehicles, it’s a tool we can use.”

Uncertainty remains, however. The city must now administer the moped program and faces a Jan. 1 deadline to implement it, but officials don’t know how many mopeds are on Oahu.

The city Customer Services Department reported having registered nearly 39,000 mopeds between 1979, when the one-time registrations started, and 2015. That includes more than 11,000 in the past five years. It’s not clear how many remain on the road or whether it will even be possible to get all of the island’s mopeds to meet the new state requirements by Jan. 1, CSD Director Sheri Kajiwara said Tuesday.

If there are too many, the department might consider phasing in mopeds past the deadline in a way that’s “fair,” Kajiwara said. “We have to come up with a plan, and then we probably have to publicize the plan to make sure everyone’s aware of how they go about complying with the new law,” she added.

Places that already conduct motor vehicle inspections will be able to inspect mopeds, too, Kajiwara said. Maui and Hawaii counties already have moped inspection programs.

Akihiro Murakoshi, owner of Honolulu-based moped retailer Mr. Scooters Hawaii and repair shop Moped Doctors Inc., said Tuesday that he is worried lawmakers are moving too quickly on a moped program that will now include the state’s most populous island.

Six months isn’t enough time to implement a well-thought-out program, and the first few months under the new law could be a “nightmare” as everyone works to adjust, Murakoshi said through a translator.

Murakoshi said he worries the program could lead to a rise in thefts of moped parts, with some riders stealing stock parts to temporarily put on modified vehicles so they’ll pass inspections. While inspections could mean a boon to his business, they could also contribute to financial struggles for smaller stores if moped sales slump due to the increased fees, Murakoshi added.

Nonetheless, Streitz and other supporters were optimistic the law will discourage illegally modified mopeds from buzzing across Honolulu.

“It’s going to be an evolution,” Streitz said. “It’s not going to happen on Day One.”