To the best of my knowledge from what I worked out when I was changing my engine covers there are 3 variants.
790cc, 865cc (carb) & 865cc (efi)
I'm sure I found the difference between the 790cc & 865cc was the crankcase breather & maybe a couple of other differences.
As for the carb & efi 865cc, the efi has a bigger diameter gear change shaft.
