Featured In the September 2019 issue of Roadracing World:

         At the launch of the stunning six-cylinder CBX streetbike in the fall of 1977, Honda announced it would return to Grand Prix racing in 1979! Most assumed it would be with a two-stroke, but rumors of radical new four-strokes started to make the rounds.

        FIM regulations restricted the number of cylinders in the premier 500cc Grand Prix class to four. Honda engineers knew the only way to beat the two-strokes with a four-stroke was combining very high rpm combined with a very short stroke to reduce piston speed. Initial designs included a V4 with large bores with eight valves. This would have needed a tall engine to accommodate huge bores in the V between the cylinder banks.

        Designer Shoichiro Irimajiri finally settled on a V4 with oval-shaped pistons, each with two connecting rods and eight valves. This circumvented the 4-cylinder regulations, offering a compact, short-stroke engine mimicking a conventional V8 . . .

–Historic Racebike Illustrations: 1979 Honda NR500, By Mick Ofield

        Honda returned to 500cc Grand Prix racing on its own terms, convinced that it could create a four-stroke engine that would match the highly-strung, well-developed two-strokes that dominated top-level road racing. What it came up with was a design so audacious that it remains unique in racing. All the technical details are in the September issue of Roadracing World!

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