Larry Lawrence | February 8, 2017
It 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 Yamaha 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 manufacturers 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-strokes thumpers were a major part of the mix in the sport in Europe, winning numerous world championships. Gradually during the 1960s the reliability of two-strokes improved and that engine design’s lightweight and lower complexity began to take over and by the 1970s the sport had nearly entirely switch to two-stroke-powered machines.
The story of four-strokes coming back to prominence 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. Nakayama 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 Formula One car racing engine. Nakayama felt with the power characteristics of a four-stroke, the engine could be competitive 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 Supercross.
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 remembers 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 of the first guys to realize that this thing was going to be a game changer.”
Enter Doug Henry.
Henry was still on the comeback after breaking his back in the jaw-dropping crash he suffered at Budds Creek in the summer of 1995. He signed with Yamaha in ’96 and by the end of the motocross season he was starting to look like the pre-crash Doug Henry. In 1997 he actually led the early part of the AMA Supercross Series, having won rounds in Los Angeles and Seattle. Las Vegas Supercross fans probably would have never gotten to see the Yamaha YZM450F had it not been for a broken hand mid-season that took Henry out of championship contention.
Henry actually gave the American debut of the YZM at Gatorback Cycle Park in Gainesville, Florida, for the opening round of the AMA Motocross Championship. He got great starts in both motos and finished eighth overall.
The ever-diplomatic Henry said at the time the thought of being the guinea pig and racing the big four-stroke “made me nervous.” He might be holding back a bit. On the inside at Yamaha, there were indications that things were a tad more contentious than Henry lets on today. Davey Coombs wrote in Cycle News in April of ’97 that Henry threatened not to return to Yamaha for the ’98 season if they forced him to ride the YZM400F during the outdoor motocross championships that year. Henry claimed he felt switching back and forth between the two-stroke and the four-stroke threw off his timing in the stadium races, effectively knocking him out of the title chase. But the Las Vegas SX finale would change his thinking.
“Since we were already focusing on the outdoors by that point I think we decided to just go ahead and race the bike at Las Vegas,” Henry recalls. “The track suited the four-stroke because of the hard pack conditions.”
Henry was feeling good about the bike because, just that week in testing they’d figured out a major problem that had been causing the bike to cut out. He suddenly had newfound confidence in the machine.
Henry showed up at the Sam Boyd Silver Bowl with the YZM wearing red and white Yamaha livery. As practice wore on the track became hard pack, slick and actually formed a blue groove in many places, setting up perfect conditions for the four-stroke. Henry won his heat race over that year’s champ Jeff Emig. In the main Henry nailed the holeshot and led from start to finish, making history by becoming the first rider ever to win an AMA Supercross on a four-stroke.
In the final laps of the Vegas final it was looking obvious that Henry was going to win.
“All I was thinking was I hope this thing stays together,” He said. “We did all the testing and we thought we had everything dialed, but you never know under the strains of real racing in those conditions where you push it just a little harder.”
Today when a two-stroke rider is in the field fans cheer him on, reminiscing about the days of their youth, but it was just the opposite when Henry was on the YZM in Vegas.
“Everyone was really behind me,” he remembers. “I don’t know if it was just the novelty of it, or maybe they were thinking I was an underdog on the four-stroke. You know most riders started out on four-stroke play bikes and I think the bike that night brought back a lot of memories for those fans.”
The victory that May night in Las Vegas, was simply a win on a new bike for Henry. He never really knew the influence that victory would ultimately have.
“I just wanted to show everyone that if I hadn’t been hurt, I would have been right there,” Henry says of that year’s Supercross series. “I was happy to be back from my broken hand and winning races again. I didn’t realize the impact that win would have.”
