The museum at Honda’s spectacular Twin Ring Motegi racing facility in Japan houses every significant motorcycle Honda ever created—from the early production Dreams, to hundreds of exotic racing machines. Arguably the rarest among Honda’s exotics is the NR series of oval-piston road racers.
Known internally by the Honda code OX during its development, the NR500 earned its official designation in July 1979 and was entered into the Silverstone Grand Prix in August. The sole four-stroke in a field of two-stroke racing machines, the NR featured a high-revving V4 engine with oval pistons and 8 valves per cylinder, and cranked out a whopping 115 horsepower. The exotic engine was mounted in a semi-monocoque, aluminum shrimp-shell frame, and the chassis featured common axis swingarm, side radiators and other radical technologies that were kept as secret as possible. Two NRs were entered, but neither finished, and both machines fared poorly against the finely honed two-strokes of the day. But Honda wasn’t disappointed; the company merely increased the pace of the NR’s development.
New engines were soon developed, and a revised V angle of 90-degrees boosted power to 130 horsepower. Honda also developed an innovative slipper clutch to deal with the NR’s excessive engine braking, and replaced convention chassis materials with exotic carbon fiber frame spars and revolutionary suspension systems. In 1981, the NR500 made history by winning its first race, the Suzuka 200km endurance race. The legendary Freddie Spencer competed at Laguna Seca on the NR500 at the AMA National when 500cc two-strokes ruled that series, and Spencer managed to win a heat race, but didn’t finish the main event. In the Grand Prix series, the NR500 never materialized as a threat, so in 1982 Honda refocused its efforts on the NS500 two-stroke triple—a machine that benefitted greatly from technology pioneered on the NR. Spencer would bring Honda’s its first 500cc GP crown the following year on the NS triple.
Behind the scenes, Honda’s radical oval-piston technology continued to develop, and in 1987 Honda entered the LeMans 24 hour with a 750cc version of the machine. An extremely limited and expensive production version of the NR750 was released in 1992, a machine featuring more exotic technology than had ever been put into production.
Today, the legend of Honda’s amazing NR series machines lives on at Motegi, the result of boundless engineering imagination and a will to create something unlike anything the world had ever seen.