SOHC.co.uk Forums > CB750
New Main and Big End Bearing Shells
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
AshimotoK0:
--- Quote from: royhall on May 24, 2016, 07:08:30 AM ---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.
--- End quote ---
I do have a spare (bare) crank that I got miked up by my 'miking' expert and the journals were all good. Sadly he passed away last summer, very suddenly. Think it 'owes me the 'ubiquitous' 25 quid (it was off a K7 but all cranks basically the same, up to the auto), but your crank is probably recoverable anyway by the sounds of it . Yes that article by Rick Partington in CB was interesting .. the kind of article they should be doing rather than one I read on bead blasting ..where, at the end, they basically told you in CMM to give it to the experts (and pay an enormous amount of money). That mag went sadly downhill when Rod Gibson passed away :'(
BOT are you guidance on this, IMHO (Bryan, Oddjob Trigger ;D ;D ;D ;D)
ginger_jim:
--- Quote from: hairygit on May 24, 2016, 07:47:49 AM ---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
--- End quote ---
+1 sending to SEP, they will provide the shells too.
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