Honda CB650


The Honda CB650 is a standard motorcycle produced from 1979 to 1985. It featured a four-cylinder, SOHC, air-cooled, wet sump engine, with two valves per cylinder. The CB650 was a development of the CB550, itself derived from the even earlier CB500. The CB650 was the last of Honda's successful series of air-cooled SOHC fours that began in 1969 with the Honda CB750.

Model development

For cost-saving purposes, the CB650 was designed to be produced on the same production line as its CB550 predecessor, using the existing tooling. The CB650's cylinder block was a new design, but it shared the stud holes of the earlier bike, which may explain why the bike could not be a full 650cc machine. Likewise, the frame was almost identical to that of the CB550. Handlebar levers and instruments were also carried over from the earlier model. The CB650 produced a claimed @ 9,000 rpm.
In 1980, the CB650 was re-styled but there were no significant mechanical changes. After 1981, the CB650 had a modified cylinder head and new CV vacuum carburettors, and the bike was now available in either Standard or custom configurations. The latter had "cruiser" styling with a teardrop tank, chromed air-box, and smaller side covers. The 1980–1982 Standard model featured 4-into-2 exhaust pipes, a black plastic headlight nacelle, and wire-spoked wheels. The custom model featured 4-into-4 exhaust, Comstar wheels, a chrome headlight nacelle, and in 1981, dual disc front brakes and air-assisted forks.
A second generation model was produced from 1982 to 1985. In 1982, replacing the Custom, the new Nighthawk featured a re-designed tank and side covers, while the 1982 Standard model remained largely unchanged. In 1983, the SOHC engine was replaced by a new rubber-mounted DOHC engine featuring hydraulic valve-lash adjusters; and final drive was changed from chain to shaft-drive.