XS650 History.
The xs650 was designated the XS-1 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. The XS 650s valves are operated by a single overhead camshaft (SOHC) whereas almost all contemporaries in its class have pushrod valve gear.
The Yamaha XS 650 was produced until 1985. Over a quarter million XS650s in 40 different variations were produced by Yamaha between 1970 and 1985. The XS650 big twin, especially in America has developed a cult following for good reason. At the heart of the XS650 is a indestructible engine. The best parallel twin ever built. In the United States, the last model year was 1983 with Canada, Europe and other markets continuing into 1984 and 1985. However, many US models were left over due to overproduction and an economic recession and brand new 1982 and 1983 models could still be purchased in 1987 at some dealerships.
The 1970 model was designated the XS-1. Subsequent models were XS-1B (1971), XS-2 (1972), then they changed the model designation from XS to TX. It went TX (1973), TX-A (1974), then they changed it back to XS but went on with the alphabetical suffix. XS-B (1975), XS-C(1976), XS-D(1977), XS-E (1978), XS-F (1979). 1979 was the last year of the so-called “Standards” (owner’s term meaning opposite to Special) The Es and Fs also came in Special form; XS-SE (S for Special) and XS-SF. From then on it was Specials only to XS-SJ.
[...] My first bike was a borrowed 3.5 horsepower minibike in 1967, when I was 8 years old. I then went to 65cc and 100cc 2-stroke dirt bikes until I turned 16. My first street bike was a 1978 Yamaha XS-650 that I bought in 1980 when I was 21 years old. They were unique for having ball bearings for the crankshaft and aluminum rims, and both electric and kick start. The worst part about them was the vibration- they rode a lot smoother under 65 mph- at the 105 mph top speed your eyeballs were vibrating and everything looked fuzzy. They were also air cooled and very hot at stoplights in the summer. Here is some more info and photos for them: XS650 History. [...]