(01-12-2014, 08:16 PM)Splashdown Wrote: Thank you hurplepelmet. Now that is interesting. I was lead to believe that he was on a V4.
I can't think what the RS750 was based on. A CB750F?

A pleasure. From http://world.honda.com/V4-story/pc/04/

Production V4 Engine Has Ample Race Potential

In 1982, the VF750 Sabre was followed by the VF750F. While its engine had the same output figures as the Sabre and Magna, heavy engine braking caused rear wheel hop, requiring fitment of the slipper clutch designed for the NR500. The VF750F was also the first production bike to feature a double-cradle frame made from box-section tubing. The incredible potential of this machine was proven when racing versions won the Daytona 200 and many other races around the world. The VF750F was followed by a whole line-up of V-Series machines developed in quick succession, including the impressive VF1000R. In 1982, HRC (Honda Racing Corporation) was established and went on to develop many racing machines based on the VF750F. In 1983 they developed the incredible RS850R. This was followed in 1984 by the RS750R, which won the 24-Hour Le Mans endurance race and many other big races. In addition to its impressive power output, the 90° V4 engine layout eliminated primary vibration, was as narrow as a twin-cylinder engine and had its cylinders cast into the upper engine case. The design of this remarkable power unit was both revolutionary and, in retrospect, very rational. It would form the basis for many successful Honda V4 engines to come.