1947 FN M13 (500cc sidevalve single). Check out that front suspension. It's called a "trailing link girder fork" or "wheelbarrow fork." Apparently it has a lot of suspension travel.
Kawasaki Mach III aka The Widowmaker because the flimsy brakes, suspension and frame could not cope with the 9000-rpm power of that 500cc 2-stroke triple.