“King” Kenny Roberts was a great American flat-tracker and road racer, throwing his leg over a variety of special machines during his racing career.
Some of his most remarkable machines were the 500cc world grand prix road racing motorcycles he used to beat the Europeans at their own game, winning the title his rookie season in 1978 and repeating in 1979 and 1980.
The bike pictured above is the 1980 Yamaha OW48 factory racer he rode to capture his third and final 500cc Grand Prix World Championship.
Yamaha knew that the competition would be intense in 1980 so the tuning fork company added some special features to its machine.
The engine was derived from the same inline four-cylinder two-stroke that had carried Roberts to his first two titles. But the frame, painted black to avoid attention, was made of square-section aluminum tubing, a first for Yamaha.
The fork options included a set with hydraulic anti-dive, but Roberts favored the type on this machine, with externally adjustable rebound and compression damping and no anti-dive.
The engine in this machine features the standard cylinder arrangement of the previous two years, but midway through the season, the team tried reversing the outside two cylinders, placing the intake in front and the exhaust at the rear, with two silencers on each side of the bike instead of three and one.
Roberts rode this machine to victory in the first three races of the 1980 season, then hung on as Suzuki swept four of the last five rounds. While Suzuki came on strong, it wasn’t enough and Roberts won his final championship.