Honda-SOHC
SOHC.co.uk Forums => CB750 => Topic started by: Andy1976 on June 16, 2009, 09:12:36 AM
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I've managed to get my bike running and after I took it for a short run I've found oil leaking from the cylinder head.
What causes oil to leak and how do you fix it? ???
Other than this everything seems to be fine.
Thanks
Andy.
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Hi Andy are you sure its the head ? if it is then you will need a new gasket, it could also be the rev counter drive oil seal or one of the tappet covers leaking , cheers Mick.
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Hi Mick,
I'll have another look tonight, Ive gotta go to work now. :(
Thanks
Andy
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I've had another look this aft and it seems to be coming from exhaust tappet covers on 1&4 so that can be easily fixed.
But..... on start up I get quite a bit of white smoke, which seems to thin out as the bike warms up. Is this a dodgy valve oil seal or is it still burning off excess oil from the rebuild?
I used quite a bit when putting it back together and I only did 2 miles when out doing a test run on sunday.
Thanks again
Andy
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Hi Andy that sounds like an easy fix if its only the tappet covers ;), mine smoked for a while after rebuild and i used plenty of oil whilst rebuilding seems to have settled down now :), cheers Mick.
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1st time I noticed it the light wasn't that good so I didn't see the covers leaking. ::)
Some of the guys on the US site said not to worry too much about the smoke, it'll settle down after I've put some miles on her.
Phew!! panic over.
Cheers
Andy
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It's still leaking!!!!!!!!!! >:(
The tappet cover seals have been replaced and four bolt holes have been heli coiled as the rocker cover was also leaking.New rocker gasket. It looks as if it's leaking between 1+2.The head gasket seems fine. I was on the phone to a guy in Wetherby this morning and he said it may be the round disc under the cam carriers that may be causing it.
These round discs were replaced with new ones when I rebuilt the top end.
Any Ideas on this. (This bike will not get the better of Me) ???
Andy
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Oil can leak arround those "pucks" if you didnt use a sealant on them.
Also the stud/bolt holes on the cam bearings are through holes and if not in excellant order can leak oil down the threads.
But first have you checked the tacho cable seal
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Hi Brian,
The tacho cable seems OK.
Thinking back to when I rebuilt the top end, I'm pretty sure I didn't use any sealant on the pucks so I'm guessing it's this that causing it to leak.
When I've got it stripped down (again ::) ) I'll also check the bolt hole threads.
What sealant would you recommend?
Thanks again
Andy
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Personally I would use Silicone VERY sparingly, but then i have been doing it for years and know where not to get the goo so it doesnt block anything, The guys on the US site have lots of different ideas on the subject, would be worth looking at mike reike (i think thats spelt wrrong) posts
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Hi Andy i used Hylomar Blue when i rebuilt my engine , just make sure you get some all around the recess the pucks sit in then they should seal up ok ;), cheers Mick.
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Ah good old Hylomar as use by the best----Rolls Royce
JUST NOT TOO MUCH
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Much better than silicon Hermetite.
A while back I was given a'69 G plate 175 which had a seized cam.
Once everyting was fixed I couldn't get any oil up the stud to the head. Stripped off the clutch case and found a nice blob of orange Hermetite sitting in an oilway.
A previous owner had done some work and used too much with disastrous results.
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I use talc to indicate where oil leaks emanate from.Clean off the engine and apply talc (or that unused self-raising flour that is always bought but never used).