Monday, May 11, 2009

Yamaha OW48

Kenny Roberts' 1980 Yamaha OW48

For a lot of us, he was King Kenny. This was his throne.

Kenny Roberts wasted no time proving that he was something special by winning the AMA's Grand National Championship in 1973, only his second year on the circuit, then repeating that feat in '74. And even though he lost the title to Gary Scott in '75, he showed unprecedented versatility, winning at least one race from every one of the five types of competition that made up the series — mile, half-mile, short-track, TT and road race — in a single season.

But that was just the start. In 1978, Roberts went grand prix racing in Europe. The upstart rookie entered three of the most competitive classes — 250cc, 500cc and 750cc — and a third of the way through the season, he led two series and was second in the other.

Eventually, Roberts consolidated his efforts to focus on the premier 500cc class. He won it that year and repeated in 1979, overcoming a broken back suffered in a high-speed, pre-season crash.

The next year, 1980, would prove to be his last world-championship season. And this is the bike he rode that year.

By then, Roberts was the favorite. But that season would be no victory march. Suzuki wanted the title bad, sending waves of riders after Roberts, including American Randy Mamola.

Yamaha built a number of new tricks into Roberts' machine. The engine was derived from the same inline four-cylinder two-stroke that had carried him 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. In the end, he held off Mamola to win his final championship.

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