Honda RC149

The Honda RC149 is a Grand Prix racing motorcycle that Honda raced in 1966, a technologically advanced, high-revving 125 cc DOHC air-cooled inline five. On it Luigi Taveri won the 125 cc riders' championship and Honda the constructors' championship. After winning the 125 cc titles in 1961, 1962 and 1965, Honda saw two-strokes improving and needed a better machine, and 24-year-old engineer Shoichiro Irimajiri led the project. Because a four-stroke has a power stroke only every two crankshaft rotations, he made the engine rev higher with five cylinders and four-valve heads, reducing the reciprocating weight. The RC148 forerunner, introduced at the final round in Japan in 1965, is effectively two and a half 50 cc twins, 33 mm by 29 mm bore and stroke, making 34 bhp at 20,000 rpm.