Honda NR500
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The Honda Motor Corporation NR500 protoype racing motorcycle was first produced and tested in 1979. It was Hondas first foray back into International motor racing after quitting some 10 years earlier. However, Honda decided to re-enter competiton, in a class that had long been the preserve of two-strokes, with a revolutionary four-stroke engine. Instead of using circular pistons, the engine used oblong pistons rising and falling in an oblong bore. The reason for this was that many years previously, a limit of four pistons was set for the 500 GP class, and it was reckoned that by using normal circular pistons, four-stroke could never be competitve using the same capacity limit.