for the NR500, and Honda subsequently redirected its Grand Prix campaign in the form of the NS500 two-stroke machine. In 1983/84, a 250 cc V-twin using a supercharger and the 8-valve oval piston technology was developed but never seen in public. The oval piston concept continued in the NR750 endurance bike, which made a brief appearance during the 1980s. Finally the technology was transferred to the road, at least on a limited basis, with the bike simply referred to as the 'NR'. One of the most expensive road motorcycles yet offered for sale, a limited number of the NR models was sold in 1992 with a 750 cc version of the engine capable of developing approximately 125 bhp at 14,000 rpm in standard form. Although a heavy machine by modern standards, it incorporated a range of technologies and design features that have now appeared on more common models. Concept In 2008 Cologne Motorcycle Show, Honda unveiled a V4 Concept Model to celebrate the company's 60th anniversary. References External links Honda NR750 RC40 model information The Oval Piston Engine (1979) From Fantasy to Reality: Completion of the 0X Engine NR Grand Prix motorcycles