I’ve been fortunate to have had conversations over the years with some of roadracing’s top builders. At Talladega in 1974, all of the factory Yamaha TZ750As were violently unstable in Friday practice; I saw Don Castro’s bike throw his boots right off the footpegs as he passed start/finish on the superspeedway. On Saturday morning, Kel Carruthers had all those bikes up on benches, their front ends off. He found a small machining error in the fork dampers, and when he fixed it, the bikes were stable and finished 1-2 (my TZ, ridden by Jim Evans, was third; I was thrilled). Carruthers later said something I have always remembered: “From now on, we’re going to have to put just as much time into the chassis as we now put into the engines—if not more.”
In 1978, Carruthers and Kenny Roberts went to Europe to race 500cc Grand Prix. At first, Kel had plenty of the usual work for the hacksaw, diegrinder and welding torch. As Yamaha refined its package, the engineers began to forbid such changes. “I’m just a parts changer now,” said Carruthers.
Erv Kanemoto earned fame and respect for building winning bikes for Gary Nixon and Freddie Spencer. When he was about to go GP racing in 1982 on Honda’s NS500 Triple, Spencer rode a pre-season test in Brazil. Kanemoto had brought a speed gun, expecting it to be useful in comparing hardware. To his surprise, Spencer went the same speed on just about everything he rode. To explain this to Honda’s legendary racing exec, Yoichi Oguma, Kanemoto said, “Do you know the word ‘compensation’?” Like Casey Stoner today, Spencer was finding a way to go fast no matter the combination. Erv gave up the speed gun and began to pay attention to which setups put the least sweat into Spencer’s helmet.
Kanemoto’s career in racing began in the 1960s when a rider had one bike and that was it. If its crank let go, Erv had to strip that engine, replace the crank and reassemble. He joked about big boxes in the Yamaha garage at Daytona in 1984, suggesting that if you could get close enough, you’d see stenciled on them: “Open this box if the bike won’t lap under 2:02,” and “Open this box if it won’t go over 200 mph.”
Soon, that was no joke: Factory transporters in Europe were filled with fresh engines in sealed containers. At any sign of a problem, a 40-minute engine change took care of it. Nobody worked on engines at trackside anymore; engines were built at the factory in clean rooms. Not only that, no one knew how to work on engines at trackside.
As seasons passed and engines became ever more highly stressed, they were changed more frequently. One year in the ’90s, Ducati was changing Superbike engines after every other practice. In MotoGP, it became the norm for a rider to use dozens of engines per season at several hundred thousand dollars per unit. When the Depression of 2008 hit, even top teams were turning out their pockets and feeling under the seat cushions to pay for this. Current rules limit each rider to six engines per season, so each must do three GPs. These engines are sealed—no service is permitted.
In 1970, New Zealander Ginger Molloy was second in 500cc GP behind Giacomo Agostini’s MV Agusta. Molloy had one bike and a helper. He changed the cranks and pistons, set compression and ignition timing—all illegal in today’s MotoGP. There was no European Union, so he also had to dicker with customs at every border crossing. He must laugh when he reads of the terrible privations of today’s riders, who are restricted to only six engines.
Steve Johnson worked for Kawasaki here in the U.S. in the mid-1970s, developing the KR250 tandem Twin like those later ridden to world titles by Kork Ballington and Anton Mang. He lived on the company’s Schenck dyno. I spent a weekend with Johnson at Loudon, New Hampshire, where Ron Pierce rode Steve’s KR to a promising win against Yamahas. In 1981, Johnson was crew chief on an Eddie Lawson European foray into 250cc GP. Three years later, Lawson would be 500cc world champion.
When Yamaha brought out its FZR750, Johnson was on another dyno at an aftermarket company, developing pipes and modifications. His work revealed that the five-valve cylinder head imposed hard compromises. If you raised the compression to make the bike accelerate, the broad combustion chambers became so thin that combustion slowed down, chopping revs and torque off the top. To get top-end, you had to open up the chamber, which meant giving up the acceleration that high compression brings. This was “the Formula One syndrome” that affected all the Japanese brands from the later 1980s to mid-1990s.
During the winter of 1992, the five-valve Vance & Hines Yamaha AMA Superbikes took a big step forward in performance. Crew chief Jim Leonard had pushed through a radical project: to relocate the engine’s five valves in a tighter cluster, nearer the center of the chamber. The aim was to reduce intake-valve masking by the nearby cylinder wall.
I thought about the problems of re-angling everything so that the seats and heads of the valves were relocated, but the tappets were still where they had to be—under the cams. This was a huge project. When I asked how it was done, Leonard said rather casually, “They have some Mazaks out there in the shop.” (Mazak is a major Japanese brand of CNC machining center.)
Mazaks weren’t the only V&H asset “out there in the shop.” Byron Hines may say little, but he accomplishes much. In our brave new world of engines as no-touch-’em “black boxes,” the intimate business of changing the valve angle of even a two-valve engine is so esoteric that most have never heard of it. To change the positions of 20 valves and then win national races with the result is off the charts. Hats off to Leonard and Hines.
Tom Houseworth has now been crew chief with Ben Spies through three AMA Superbike championships, a World Superbike title and two years in MotoGP. Houseworth says his major task in that WSBK year was keeping the Italian mechanics from changing things on the bike.
Almost 20 years ago, Houseworth was on Yamaha’s AMA Superbike team. “We’re all sitting in a big meeting inJapan,” he said. “They tell us, ‘Please give us your suggestions for how we can improve performance.’
“I raised my hand, and they called on me. I asked, ‘How about a four-valve head?’
“After that, I had to eat lunch all by myself.”
In 2003, Yamaha’s crack problem-solver, engineer Masao Furusawa, was asked to make a winner of that company’s troubled 990cc YZR-M1 MotoGP bike. Knowing management might not like what he suspected was necessary, Furusawa put the choice to newly hired rider Valentino Rossi. Four bikes were built for Rossi to test: 1) standard M1 with traditional flat crankshaft and Yamaha’s “signature” five-valve cylinder head; 2) flat crank and new four-valve head; 3) new low-inertia-torque “crossplane” crank and five-valve head; 4) crossplane crank and four-valve head.
