Yamaha XS 650 - Model History

Model History

The 1970 model was designated the XS-1. Subsequent models were XS-1B (1971), XS-2 (1972), then TX (1973), TX-A (1974), 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 the 650 "Special," which had pullback bars, teardrop tanks, and other custom features). The Es and Fs also came in Special form: XS-SE (S for Special) and XS-SF. From then on they were Specials only to XS-SG, XS-SH, XS-SJ, XS-SK. There was a Special II (Two) model designation in 1979 (XS-SF-II), 1980 (XS-G), 1981 (XS-H) which were models with fewer chrome parts and drum rear brake (1979, 1980) or wire wheels (1981) versus disc rear brake or cast wheels.

The first two model years (XS-1 and XS-1B) were kick start only, with an electric starter added from the 1972 model year on. This had a compression release added to the front left exhaust tappet cover resulting in a square versus triangular cover found on the other exhaust and intake covers. Upon removal of the compression release mechanism in 1974 due to uprated starter, the square cover at the left exhaust valve was continued.

Brake modification notes:

• Drum fronts on early models cannot be changed.
• Pre '77 & post '77 fronts have different (offset) brake discs, the wheels swap but not the discs.
• Drum rear wheel into rear disc frame needs the rear drum frame swingarm too.
• Disk rear wheel into rear drum frame needs the rear disc frame swingarm and also needs brake master-cylinder lugs welded to the frame.

Handling differences on swapping rear wheels:-

• Standard rear tire is 110/90-18. Special rear tire is 130/90-16. Because the Standard tire is narrower it will tend to steer a bit more quickly. Because the Special tire is wider it will tend to be a bit steadier in a straight line. Overall gearing is not changed from the Standard, as the two tires are essentially the same outside diameter.

1976 models had the front brake caliper moved to the right fork leg, behind the fork as opposed to in front of the fork. This placed the brake caliper nearer the axle center-line, requiring slightly less effort to steer.

Mid-'77 the front forks had a major redesign, fork tube diameter increased from 34 to 35 mm (1.4 in) and internals were changed (although this also holds true for various years of the same tube size). The entire fork assembly (with triple tree) will swap either way but fork parts are not equivalent. Also the brake caliper changed from a 48 mm (1.9 in) dual piston cast iron design for the 34 mm (1.3 in) fork to a 40 mm (1.6 in) aluminum single piston floating caliper for the 35 mm (1.4 in) forks. The brake caliper mounting lugs on the fork sliders are of different spacing for the 34 mm (1.3 in) and 35 mm (1.4 in) forks so the calipers can't be swapped.