Thanks fellas for your replies. Excuse my ignorance, like I say, totally green to this, been riding ten years but never really got my hands dirty, this is my first project.
Spanner 1 - its a four into one, silver and white. So that was the engine number not the serial number? That explains a few things. From the back of the Haynes manual using that engine number it looks like its an '82 CB900 F2-B.
Any one got any comments on these engines?
And it being a DOHC, am I still welcome to post here?
Finally, any thought: cant find any pistons, cylinders dont look scarred, what sort of problem do you think could have prompted the previous owner to tear it down and result in missing pistons but no cylinder probs?