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Jan 15, 2001

Yamaha GP Four-stroke Already Faster Than YZR500 In Top Speed

Reports out of Japan today (January 15 U.S. time, January 16 Japan time) indicate that both Yamaha and Honda are already testing four-stroke GP bikes in preparation for the 2002 racing season, when 990cc four-strokes will compete with 500cc two-strokes in the Grand Prix World Championship.

While a two-stroke Yamaha YZR500 makes about 190 horsepower, the new four-stroke Yamaha already makes over 230 horsepower and has a 10 kph (6.2 mph) advantage in top speed on Yamaha's private test course, according to racing sources in Iwata, Japan. The four-stroke's lap times have not yet equaled those of the YZR500.

The new Yamaha is thought to be a V3, although the sources would not admit to the engine configuration. If it is a V3 with round pistons, it would have to race with a minimum weight of 135 kilograms, or 5 kilograms more than the minimum weight for a YZR500 in 2002. A V3 with oval pistons will have to meet a minimum weight of 145 kilograms.

Meanwhile, Honda has been testing both V5 and V3 four-stroke racebikes in Japan and plans to announce the configuration it will use in 2002 at a press conference to be held January 29. Competing engineering teams built the machines, an approach used before by Honda to determine the best configuration for a given application.

Honda and Yamaha's initial testing contributed to Bridgestone's decision to enter the Grand Prix World Championship in 2002. Initial tests have shown both companies' new four-strokes to be very hard on existing tires made by Dunlop and Michelin. Bridgestone recently contracted Erv Kanemoto's Kanemoto Racing to test tires on a Honda NSR500 during 2001, in preparation for the 2002 racing season, although no official announcement has been made yet.