Honda's announcement that it was returning to 500cc Grand Prix racing in 1979 with their 'New Road' NR500 V-four racer that used oval pistons. Honda's absence of 12 years caused less of a sensation than the news that their GP contender was a four-stroke, as at the time two-strokes seemed to rule GP races.
A Fake V8
Moreover, it quickly became apparent that this engine was really an eight-cylinder whose pistons had been "welded" in pairs to meet the rule prohibiting more than four cylinders in the 500cc class In fact, the pistons and bores had 3 cross section like a rectangle with semicircular ends, This ploy allowed the engine to run at over 20,000rpm, producing a power output equivalent to that of a two-stroke. The oval piston allowed for eight valves per cylinder which generated more power due to the increased air / fuel mixture throughput and compression.
And that wasn't the only original feature of the machine: its 16-inch wheels were something new at the time, as was its front fork with external springs and its lateral radiators -which even as late as 1992 had not been adopted by other makers, Nothing like its streamlined light-alloy monocoque exoskeletal frame has been seen since, Despite all Hondas efforts, the career of the NR was a fiasco, which led the company to create the NS, a two-stroke three-cylinder that Spencer rode to the world title in 1983. Nicknamed "Never Ready", the NR continued as a test vehicle long after its racing days were over, including such variations as the NR750.
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