NR500 was an innovative racing motorcycle developed by Honda HRC in 1979 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 its automobile division.
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. 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 drag, the bike also used 16-inch wheels instead of the mainstream 18-inch versions.
