The Honda V-Four heritage can be traced back to Soichiro Honda’s first four-stroke engine designed in 1951 by Kiyoshi Kawashima. Throughout the 60’s Honda had outstanding success with it’s four-stroke engines, both on the road and track. During a 10 year absence from the race track between 1967 and 1977 Honda used the lessons learned from racing to launch the worlds first superbike, the CB750. In 1977 journalists gathered in Japan for the launch of Soichiro Irimajiri’s six cylinder CBX and now company president Kiyoshi Kawashima used the occasion to announce Honda’s return to Grand Prix racing. Honda would race in the 500GP’s in 1979, and they would do it with a four-stroke. Honda had kept up with the two-strokes on the racing track by adding extra cylinders and gears to their four-stroke engines, producing a six cylinder 17,000rpm 250 in 1964 and a five cylinder 125 in 1966. However during Hondas absence from the race track the sports governing body had changed the rules and restricted the 500cc class to four cylinders! Kawashima had two years to design a new engine and placed CBX designer Irimajiri in charge of the New Racing project. Irimajiri would have loved to have added more cylinders to his engines but the new rules restricted him to four, actually the rules specified four combustion chambers. Legend has it that while sitting in a traffic jam in Japan, Irimajiri was struck by the design of the traffic lights, the lights were contained in oval housings. If he could make the cylinders of the new 500 four-stroke engine oval they could pack in eight valves, four inlet and four exhaust, effectively the motor would be a V8 but with adjacent cylinders conjoined – the V4 was born. The patent for the oval cylinder engine was filed in March 1978 and by 1979 Honda’s engineers had produced the NR500(0x). What the public saw at Silverstone in August 1979 was completely different to the state-of-the-art motorcycles of the time. Honda’s team of engineers, who had no previous racing experience, had designed the ultimate solution to the design problems experienced on the racing track, from the suspension to the chassis, features that we now take for granted on modern motorcycles were first seen on the NR500, and of course at the heart of the machine was the new oval-piston V4 engine. Each cylinder had four inlet valves, four exhaust valves and two pistons with the opposing cylinder pairs angled at 100˚ making room for the twin-choke carbs to sit nicely in the middle of the Vee. Drive to the NR500’s cam shafts was gear driven and the 0X engine eventually made 115bhp. Whilst the NR500 had met the 1979 deadline and its design was a success, on the race track it was a failure. Further variants of the bike found some success. In the 2X model ridden by Freddy Spencer the angle between the cylinder heads was reduced to 90˚ and the power output increased to 130bhp, another 5bhp was achieved with the 3X engine. The true success of the NR500 came from the experience Honda’s research and development team gained from its production and design. Oval pistons may not have been the way forward but the V4 was the ideal power plant for the track and road. This history page is still under construction V4 History text has been adapted from Julian Ryders "HONDA'S V-FORCE - the four-stroke V4s on track and road"