No XS: Yamaha XS400 Twin(s) – BikeBound
After all, its two-stroke sibling, the RD400, had been the fastest of the 400s, and everyone was curious what Yamaha could do with a 400cc four-stroke. While heavier and less sporting than the RD, the XS posted respectable numbers for the day. The SOHC straight-twin engine made 36 horsepower at 8500 rpm, capable of pushing the 400-lb …