Pistons and Bore
 

I've got a 1996 918cc CBR900RR motor that is claimed to have been bored over in piston size to the specs of an 1100cc. My only question before I go tearing into this thing is concerning the possiblity and probability of this bore.

In my mind the walls would be tooooooo thin, but what do I know about it? That's why I'm asking the questions and you're giving the answers.

RE: Pistons and Bore
 

Hello??????????????????????????????
Is anyone there?

RE: Pistons and Bore
 

The largest pistons available for your 919 is 997cc. They require oversize sleeves to be installed. So I figure there is ZERO chance your motor has been bored to 11oocc.

Check here for piston availibility;
http://cbrzone.com/pistons.html

Jay

RE: Pistons and Bore
 

You can't listen to backyard mechanics on engines. My buddy just bought a VX800 and took it into a shop for valve maintenance and such. He was told that the engine was damaged and had to be bored out so they went ahead and did the most they could. So it's now like a VX1200. First words out of my mouth was WTF!!! So I asked my local shop guy, certified mechanic and very trustworthy.... He explained without changing anything major (like the cylinder itself or sleeves) you'd be hard core to bore out a cylinder to 3mm, which would be taking the 800 to 820ish. He said these were rough numbers and he'd have to research and do measurements to give me exact numbers.

RE: Pistons and Bore
 

970cc is the largest we know of. It could be bigger if it had a stroked crank,. but that is very dificult to do with the Honda because of the cylinder block, case design.

Jay