Harley-Davidson Inc., the Milwaukee manufacturer of the best-selling big bikes in the country, has pulled the plug on its effort to obtain federal trademark protection for the syncopated “potato-potato-potato” chug of its idling V-twin motorcycle engine.

The company Tuesday said it has dropped applications for federal trademark protection for various design elements on its motorcycles, including its teardrop-shaped gas tanks, the curve of its front and rear fenders and the overall shape of its motorcycles.

A Harley-Davidson spokesman said the company, which has been battling opposition to its trademark applications from other motorcycle makers for almost six years, is tired of tossing tens of thousands of dollars into a legal case with no end in sight.

Harley feared that the thump-thump-thump of its engine, a noise that can thrill or chill, depending on the listener’s attitude toward bikes and bikers, would become the next nylon--the early DuPont synthetic whose name wasn’t protected and fast became a generic term.


But the bike maker was roaring up a rocky road when it asked the government for a sound patent: As of 1998, only 23 of nearly 730,000 active trademarks had been issued to protect a noise, and most of those were for artificial arrangements, such as the roar of the MGM lion, NBC’s three-note musical chime and the spoken “AT&T;” superimposed over musical sounds.

Although the U.S. Patent and Trademark Office had not ruled on Harley’s applications, agency insiders have privately questioned the motorcycle maker’s ability to prove that its designs or the sound its engines make are unique to Harley-Davidson products.

Other motorcycle makers that have produced so-called classic or cruiser motorcycles--including Honda Motor Co. and Yamaha Motor Co. of Japan--have argued that the sound is a characteristic of all V-twin motorcycle engines and that the design themes predate development of the Harley bikes.

The maker of Fat Boy, Softail and Road King bikes--made notorious by outlaw motorcycle gangs in the 1950s and legitimized in the ‘90s by legions of lawyers, accountants and others who enjoy taking to the road on the throbbing cycles--said it is satisfied that its customers know well the look and sound of a Harley and will not be fooled by imitations.


“If our customers know the sound cannot be imitated, that’s good enough for me and for Harley-Davidson,” said Joanne Bischmann, vice president of marketing.