Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/783081
CN III ARCHIVES BY LARRY LAWRENCE I t may be hard to believe, but it's been 20 years since Yamaha, with rider Doug Henry, turned the motocross world on its ear with Henry's victory at the 1997 Las Vegas Supercross aboard the revolutionary Ya- maha YZM400F. It not only marked the first four-stroke victory in AMA Supercross competition, it also marked a major milestone in the evolution of the sport. Fairly rapidly the other manufac- turers followed Yamaha's lead into the four-stroke realm, and motocross and supercross racing were forever changed. Back in the pre-American days of motocross, four-stroke thumpers were a major part of the mix in the sport in Europe, winning numerous world cham- pionships. Gradually during the 1960s the reliability of two-strokes improved and the engine design's lightweight and lower complexity began to take over. By the 1970s the sport had nearly entirely switch to two-stroke- powered machines. The story of four-strokes coming back to promi- nence starts with Yamaha engineer Yoshiharu Nakayama. According to Doug Dubach, the American racer who test-rode the prototype and helped develop the production Yamaha, Nakayama wasn't your typical "by the book" Japanese engineer. Na- kayama headed a small division within Yamaha that encouraged out-of-the-box thinking. They helped develop Yamaha's superbike and eventually MotoGP engines, as well as a Formula 1 car racing engine. Nakayama felt with the power character- istics of a four-stroke, the engine could be competi- tive in motocross and he wanted to prove it, in spite of skepticism from many of Yamaha's top execs. Dubach was testing the YZF project and he admits he was even unconvinced, when he originally heard of the plan, that a four-stroke could be competitive in motocross and super- cross. It was early in 1996 and Dubach remembers how unfinished the motorcycle looked when he saw it for the first time. "It was very, very raw," Dubach re- members of the prototype Yamaha four- stroke MX machine. "It was in its early stages with billet cases, all the plastics were made of fiberglass, so it was a very one-off unit. When they first told me about it I had visions of Spud Walters on a hopped up XR400, and I was like, 'Oh, I don't know.' I was definitely not overwhelmed with the prospect of testing it. "The first time I rode it was at Carlsbad and it was fair, you know, it was a little heavy, a little slow. You've got to start somewhere. By the time it came back the second time, I began to think, 'Man, this thing could really be competitive.' They'd go back and do their homework and every three months or so we'd get an updated versions and man it started getting really good. I was one P108 20 YEARS OF FOUR-STROKES Doug Henry's win on the four-stroke YZ400M at Las Vegas in 1996 marked the beginning of a new era of supercross/ motocross racing.