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CB750 / Re: Surprise 812 Yoshi Pistons - but will they work for me
« on: August 04, 2022, 01:42:31 PM »When I was in the market for a bigger piston kit for my CB750F2 I rode down to Dixon Racing in Godalming and spoke to the man himself. He didn't have any 812cc (64mm) piston kits in stock at the time so I bought the 823cc (64.5mm) kit instead. This was just a straight overbore from the 61mm standard bore that gives that engine the 736mm size. It is my understanding that 836mm (65mm) is the maximum that the sleeves will take before needing punching out & replacing with thicker ones.
I had the barrels bored to size then honed to clearance by a colleague that had a boring bar and a stone hone. As far as I can recollect (this was back in 1981) the hone to clearance was standard Honda specs as the pistons are cast, not forged, which have a different spec.
I have some spare piston rings that are surplus to requirements that I am willing to sell. I knew I kept them for a reason.
PM me if you are interested.