I have a '89 GSXR 750 with what seems to be a transplanted motor in it (749 cm, not 748cm.) I was planning on rebuilding the motor over the with and overbore kit and was just trying to get a bearing on the exact year on the engine itself. I know that '86-'87 and '90-'92 are basically the same motor, except for shims or something like that. My factory service manual doesn't seem to be of much assistance on this subject. The crankcase I.D.# is:R716-103348. Thanks.