We remember the beginnings of U.S. Superbike as wobbling, power-laden, four-cylinder, Japanese high-bar sit-ups in the hands of riding greats Reg Pridmore, Wes Cooley Jr. and Eddie Lawson. Yet the fact is that the first Superbike championship was won by Reg Pridmore on a BMW flat-Twin and Ducatis, Moto Guzzis and BMWs were to continue to win races, including Daytona. How could 80- to 90-horsepower Twins stay with 140-hp rocketships? The answers are: lighter weight, better handling, better brakes and, at least initially, preparation by experienced teams.
One hundred and forty horsepower is useless even at Daytona if your chassis is so flexible at speed that you can’t pin the throttle. At twisty tracks like Sears Point and Loudon, four-cylinder power just pushed streetbike brakes into early fade and failure. Light weight boosted acceleration and direction changing. And, at least at first, the Twins were built by experienced people while the four-cylinder teams learned by doing.
Superbike evolved out of a California production series that the AMA adopted as “Superbike Production,” initially, from 1973 to 1975, including engine displacements from 250cc to 1000 in separate races. This was intended to provide an everyman’s alternative to the GP-style 250 and Formula 750 pro classes, but the immediate popularity of one-liter four-strokes made them a major class for 1976. Pridmore’s championship on a BMW owed much to the fact that its builders at Butler & Smith had been racing the flat-Twins since 1974. Mike Baldwin’s 1976 Loudon win on a Moto Guzzi was also experience-based: from the shop of veteran Reno Leoni. Cook Neilson’s 1977 Daytona win on “The California Hot-Rod” bevel-drive Ducati drew on the resources of U.S. specialists like Webster Gear, dyno expert C.R. Axtell and airflow pioneer Jerry Branch. These European Twins all handled decently to begin with, had capable brakes and had previous history in racing.
The four-cylinder bikes—initially just Kawasaki, and from 1978 onward Suzuki, as well—had not been designed with racing in mind. Increasing their power through engine modifications at first magnified their problems with weight, weight distribution, stability and brakes. In the beginning, the liter bikes actually lapped slower than AMA 250s, but the pace of learning accelerated. Steering heads were cut out and re-welded with more head angle. Chassis were stiffened with tubes, plate and gussets. Engines were moved forward so more power could be used without loss of turning ability from front-end lift. Swingarms were braced. To stop brake-disc warping, U.S. Kawasaki developed its own production technique.
Early four-cylinder engines were fragile and tuning methods improvised. Some teams stacked on 12:1 compression, cranked in 45 degrees of ignition timing and hoped the things would last. Rod bearings tied up, and rods punched through cases. One morning as I walked through the Daytona garages in those early years, I counted five wrecked sets of Kawasaki cases and three Suzuki. Driven by necessity, teams worked through the night, and overtired mechanics made mistakes. Failure is a powerful teacher.
Although the AMA had intended Superbike as a grass-roots class, success required serious engineering. Under the surface, a dynamic process was at work. To reach their potential, the four-cylinder teams had to transform their machines piece-by-piece from production motorcycles into purpose-built racers. Factories engineered stronger clutches, close-ratio gearboxes, improved connecting rods and more reliable valve springs. Roadracing required more than power from engines; it required a pulling range wide enough never to leave the rider stuck on a corner exit with his engine just below its torque threshold.
As Superbikes came around on lap one of a race, first you would hear the strong, full sound of the three or four factory bikes tearing past. After an interval would come last year’s factory bikes, which had been sold to private teams. Then, after a longer period, would come what one factory team manager called “smoking junk”—bikes built by persons with more enthusiasm than engineering, using aftermarket drag-race parts intended to go only 1320 feet.
Grass-roots or not, race fans loved the spectacle of roaring monster motorcycles, their riders sitting bolt upright, wobbling and weaving at high speed. This was heroic!
Yoshimura switched from Kawasaki to Suzuki in 1978 and won Daytona four times in a row, plus the 1979 and 1980 Superbike titles. Kawasaki hired a two-stroke dirt-track specialist best known for his 490cc Yamaha Singles: Rob Muzzy. At first, he was asked to do cylinder heads. They worked because Muzzy reasoned that traction on pavement at high lean angle was just as sensitive as dirt. That meant smooth power was best. Then, they asked him to do engines and finally, whole bikes.
Honda joined the series, ordering titanium valves by the crate and sending out cylinder heads to all the top airflow wizards. Cams were ground in 5-degree increments of duration. Everything was tested and soon, dyno-uprooting power was the result.
They called him “Steady Eddie” but what people were seeing were: a) Lawson’s totally championship-centered outlook, which did not insist upon winning every corner or even every race; and b) the effects of his preference for a stiff steering damper. Muzzy’s best engines made 150 hp at 10,250 rpm. Smooth power was key.
Rob Muzzy’s holistic approach to racing helped Eddie Lawson become Superbike champion in 1981 and ’82, continuing with Wayne Rainey’s title in 1983. The modern era arrived that year, in the form of the AMA’s cutting Superbike displacement to 750cc and Honda’s decision to build the revolutionary liquid-cooled V-Four Interceptor. Honda had intended the Interceptor as a “homologation special”—a production bike with racing features, built only to legalize their use in a production-based class. But the market had changed. Word spread fast (“This thing handles great!”), and they flew out of showrooms. Suddenly, riders wanted these new full-capability motorcycles. These bikes didn’t have to be completely re-engineered to go racing, like the behemoths of the ’70s. All they needed were tires, a shock and detail changes to go production racing. The immediate result was the new so-called “Supersport” racing classes. In 1987, the FIM in Europe followed the U.S. lead, creating World Superbike.
The chassis and suspension technologies that had been forced into being by Formula 750 and 500cc GP two-strokes of the 1970s were now incorporated into new liquid-cooled four-stroke production bikes. Superbikes have looked just like GP racers ever since.
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