cb750 FB DOHC engine rebuild help neede please.

hi every bod,

i'm rebuilding my cb750fb engine after it snapped a camchain and bent
two inlet valves! have decided to change the main bearings and possably

the big end bearings too. have found the crankcase code which is b. but

on the crank shaft is 3 a's and 2 b's on the flywheels. does this sound

right? that three of the mains are one size and the other two
different? and does anyone now where to get the other code off the
crank for the big ends? all the con rods have 1's on them but not sure
what or where to look on the crank for the other codes. any help would
be great,


cheers terry

 

If I were you I'd try to find a replacement engine instead of rebuilding
yours. These 750s and also the 900s were notorious for
camchain/guide/tensioner problems. I have personally seen 3 of these where
the camchain has 'tunnelled' through the front of the barrels! The cost of
the top end work alone with parts, labour and gaskets would make this
uneconomical, never mind the bottom end stuff.
Unless you're *really* attached to this bike, cut your losses and get a
later CBX750. These were a much better bike all round, with none of the
horrors associated with the 750/900FA and FBs.

JB