With the stock cb650 liners you can get away with 62mm ID bore.
(However you can use the stock cb650 head gasket up to 61mm.)
I have found that CB900 liners are good enough to work.... but only when going 65mm or bigger, as the cb900 has a 64.5mm bore already.
And the cb760 pistons that are useable, are:(from what I have seen so far)
1.) overbore kits for the 750(the 836, and 812 kits in particular) - they tend to give the cb750 a bump in CR, and the dome is needed for the 650 head.
2.) '77/'78 cb750 pistons with the raised dome
DO NOT try with the '69 through '76 cb750 pistons in conjunction with a 650 head... unless you want to run a turbo.
Every window an opportunity.....
The '79/'80 cb650 head is perfectly aligned for use with cb750 carbs BTW...
According to Soos' info on using 750 high dome pistons with the 650 liners, and the lack of availability of the 750 liners (tried looking but can't find right now) should I just go with the stock SOHC 650 liners?
I'm also planning on lightening and balancing my crankshaft to help out. Also seen some people talking about running stock GSXR connecting rods because they were more light weight. Anyone know if they'll be kosher with the 550/650 Big bore hybrid?
Is there someone besides me using GSXR 1000 rods?
Mine now have the proper bearings and new bolts installed, but not in a running yet.
I have LOTS to do before they get running(unfortunately).
The GSXR rods have the same ID where the bearings go, and the shell bearings are the same thickness.
The GSXR crank has the same stock specs and tolerances(nearly) as the CB650 crank.
Center to center of the GSXR rods(bore to bore) are IDENTICAL to the cb650 rods.
IF you can run cb650 rods, then you can run GSXR1000 rods.
BUT **************BE CAREFUL***************
There are only a few years (mine are '06, just checked) that use the proper style of bearings.
I'm still researching rod alternatives.(found some nice options, but some are just flat out pricey!!) The GSXR rods seem to be the only CHEAP(yeah... $300 later for bearings and bolts... cheap.....)
But still under the $1700 tag I got for custom rods, or 1200 for -2mm stroker GSXR rods(I got pistons that would work with that combo though)
If I were loaded I would have a personal shop, and my own website full of tidbits I have learned for others to copy at will......
Ahhh.... but all I get is a kick in the nutz, and a year older.
l8r