SOHC.co.uk Forums > CB750
New Main and Big End Bearing Shells
adriangsmith:
Thanks all,
No pits on the crank shaft just the faint score lines.
I'll give it a wipe over and take some more shots.
Big thanks for the service bullitins Ash, very informative.
Adrian
adriangsmith:
cleaned and checked. no obvious ridges on the mains but they feel a little rougher than i would expect.
Also included an image of the old main shells, all of them worn pretty much the same as these.
adriangsmith:
The cam journals are what caused me to strip the engine again.
It suffered a top end oil feed failure due to a grain of sand stuck in one of the metering jets!
Found a new cam tower, just need to find a camshaft now as the right hand end is chewed up beyond repair.
Oil pump is on my list for a strip and rebuild.
Must admit the engine seems to have had a hard life and lack of maintenance.
When i bought the bike it had not been on the road since 1986.
I did a top end rebuild to replace the cam chain and tensioners, tensioner wheel was completely worn away, blade guide slots in cases worn as well.
So here i am again doing the job properly with a full rebuild.
Black shells readily available from DSS and strangely enough are cheaper than the others. but will probably follow your suggestion and go for a set of browns.
Thank you all for your help and advise.
royhall:
Whilst there's no facility for regrinds you can have the journals micro polished. Not sure who does it, but Rick Partington of Classic Bike had the 400 he was building done. May not need it though.
hairygit:
Before completely giving up on the can, give S.E.P. in Kegworth a call. I gave seen them repair cranks that look like ploughed fields by submerged argon arc welding the journals, then grinding back to original spec, and the crank is then good for many years to come. Chances are the journals on your cam may respond to the same treatment, and may prove easier and cheaper than trying to source a replacement.
Sent from my X6pro using Tapatalk
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