The Yamaha XS650 is a middle sized motorcycle from the Yamaha Motor Company.
In 1968 was the first introduction of this motorcycle and was produced all the way until 1979. The “Special” cruiser model was introduced in 1978 and produced through 1985. The XS650 began with the 1955 Hosk SOHC 500 twin. After about 10 years of producing 500 twin, Hosk engineers designed a 650 cc twin. Later the Hoskcompany was acquired by Showa Corporation, and in 1960 Yamaha had bought Showa with Hosk’s early design of 650 cc twin.
When the Yamaha XS 650 was launched in 1968 it had one of the most advanced engines in its class of large parallel twin motorcycles. The engine and gearbox are unit construction with the crankcase split horizontally for ease of assembly whereas almost all contemporaries in its class in 1968 are either unit construction with a vertically split crankcase or pre-unit construction with separate engine and gearbox. In 1968 only the Laverda 750S, also launched that year, matched the XS 650’s modernity of unit construction and SOHC valve operation.