NR500 was an innovative racing motorcycle developed by Honda in 1978 to compete in Grand Prix motorcycle racing. The NR stood for New Racing.
The motivation behind the NR500 was company founder Soichiro Honda's desire to compete using four-stroke engine technology since the majority of motorcycles manufactured by Honda used four-stroke engines. When the FIM announced new regulations for the 1968 Grand Prix motorcycle racing season that limited the 500 cc engines to four cylinders, this gave an advantage to teams using two-stroke machinery. Honda decided to withdraw from motorcycle racing to concentrate on Formula One racing.
In November 1977 Honda announced it would be returning to motorcycle Grand Prix racing using four stroke technology. Even though two-stroke engines dominated motorcycle Grand Prix racing in the late 1970s, Honda felt bound by their convictions to race what they sold and thus decided to compete using a high-technology, four-stroke race bike. Since a conventional four-stroke, four-cylinder engine could not produce the same power of its two-stroke rivals, Honda had to increase the valve area in order to be competitive. The rules at the time allowed up to four combustion chambers so honda designed a 32 valve V8 with four pairs of linked combustion chambers. Despite a common rejection from most european and even japanese design crews over the revolutionary use of a V4 config alone, Honda's new HRC made the 32 valve hybrid. The main gain from the oval or "sardine tin" piston was surface area, in a time when piston heads for GP racing where forged steel, anything that made the engine deliver more torque was an advantage!
This then evolved into an innovative engine with four oval-shaped cylinders. The oval cylinders allowed room for 32 valves and eight spark plugs, the same as that of an eight-cylinder engine while staying within the four cylinder rules limit. Another innovation used on the NR500 was its monocoque body which wrapped around the engine like a cocoon and helped reduce weight. In an effort to reduce wind resistance, the bike also used 16-inch wheels instead of the mainstream 18-inch versions.
Honda overcame significant manufacturing problems to develop its oval cylinder technology and by late 1979 the bike made its much-anticipated debut at the British Grand Prix ridden by Mick Grant and Takazumi Katayama. Both bikes retired, Grant crashing out on the first turn after the bike spilled oil onto his rear tire. Katayama retired on the seventh lap due to ignition problems. Honda persevered for two more seasons but never managed to make the bike competitive. The monocoque frame had to be abandoned because it made it too difficult for mechanics to work on the engine during races. The 16-inch wheels also had to be abandoned for 18-inch wheels. American Freddie Spencer was able to reach 5th place at the 1981 British Grand Prix before the bike broke down. The NR500 never managed to win a Grand Prix, a thirteenth place by Katayama at the 1981 Austrian Grand Prix being its best showing.
Honda decided to abandon the project and designed the NS500 two-stroke bike to compete in the 1982 season. Spencer would ride the NS500 to Honda's first 500 cc world championship in 1983. Ultimately, what doomed the NR500 project was that Honda had tried to develop too many technologies at one time. The NR500 did experience a few successes. Freddie Spencer rode the NR500 to a heat race victory at Laguna Seca in 1981 and Kengo Kiyama won the Suzuka 200 kilometer race that same year.
4 Stroke Racing
Honda used the original NR project to be based as their marketing tool for back-home and/or Honda brownie points to lure people towards the development that Honda made in favour of more economic 4T engines. The common trend from japan was light 2T engines and spindly frames, this was not the best thing as many in Honda corp (pre HRC) disliked the almost unfair advantage of higher-revving lighter bikes. Despite the on-shelf disadvantage, Honda bikes where often seen as the low-maintenance Japanese-barge of motorcycles. While Japans engineers relentlessly sued to follow a horse-power-war for over 30 years, Honda relied on innovations to better them over the iron facts that, BHP wins races.
As HRC could no longer produce fine inline-6 cyl bikes for GP racing, they removed themselves from the GP circuit, to pursue F1 dreams, as this was clearly a smoke screen in the eyes of many Japanese, a 2T return to GP was clear from the start. However, the fruits of the NR (dubbed Never Ready project by cynical europeans) Project was Honda's new found love for V4 engines. The unlikely place to see the first competitive V4 was, of course WSBK, despite a massive amount of AMA and manx TT success, the ability for only the V4 RVF (RC 45) machines which where raced in the hands of such stars as Carl Fogarty and Aaron Slight made it a machine to be set aside as one of the "100 greatest motorycles of all time", lineage that would not have been thought about enough without the fabled NR500.