Hi,
Don't really know how to answer this one as the US models were different to the UK, but I'll have a go.
The Honda CB750 SOHC (single over head cam) was produced from 1968 to 1978, originally when I first bought a CB750 they were purely known as Honda fours because there was no other 4 cylinder Honda's, rightly Honda plastered 750 four on the side panels and every where else to show off ! So this may be were you have been confused, some people call them 750 fours, some people call them CB750's.
In the SOHC production run the bikes varied from the sports tourers labelled
CB750K's and the latter more (?) sporty CB750F models which were produce alonside the K's. The CB750F's were also tagged as Super Sports (SS). The engine changed internally, and the cosmetics changed quite a bit over the years. So the real difference is in the model either CB750K or CB750F.
Hope this helps
Dennis
