Sen. John C. Danforth (R-Mo.) remained remarkably cool when high-powered Japanese officials fussed and fumed over his retaliatory trade proposals. But how well will he cope with 140,000 irate motorcyclists?

The question arises as the American Motorcyclist Association mounts a strident campaign to fight a Danforth bill that would ban "superbikes" -- those rocket-like Japanese motorcycles made popular by Tom Cruise in "Top Gun."

Dubbed "killer bikes" by critics, the new high-performance motorcycles can accelerate from zero to 60 mph in 2.7 seconds, according to Danforth, and "top out" at 160 mph. The bikes are so fast and dangerous that the Japanese have virtually banned their use domestically, while promoting them overseas.

"Indy 500 race cars have no place on public streets and highways," said Danforth, the ranking Republican on the Senate Commerce, Science and Transportation Committee, who wants superbikes restricted to private race tracks. "Killer motorcycles have no place on neighborhood streets."

But the motorcycle association has sounded the alarm to its 140,000 members, warning that the bill is so vaguely worded that the ban might be construed to apply to other types of motorcycles. "If passed, it would send a shock wave through the entire motorcycle industry," declared American Motorcyclist, the association's official publication.

While both sides agree that safety is a major issue in the dispute, some association officials contend that Danforth is also using the bill to get back at the Japanese for unfair trade practices.

"I think he reflects pretty strong anti-Japanese undertones or overtones," said Robert W. Rasor, the group's vice president for government relations. "I see this {sentiment} as possibly being carried over into this {motorcycle} market where the Japanese are dominant."

Stephen Hilton, Danforth's press secretary, dismisses Rasor's assertion as "ridiculous."