Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: alexdecker on August 19, 2021, 06:57:52 PM
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Hey all
I installed a new gasket and o-ring set the first time I took the top engine apart on my CB550F2 from 1977 . Sourced it from CMS. The bike still leaked oil. So I sourced a Vesrah complete gasket set and put that in instead. The bike is still leaking oil from the top. I have made sure that all surfaces are clean and even, and I even used some extra sealing silicone the second time around to be sure. And still it leaks. I am running out of ideas as to what to do.
Has anyone else had a stubborn leak, that they finally got rid of somehow?
- Alex
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Are you sure its not the end cap O rings that are leaking? they are very, very prone to it.
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I took some photos. It's in each end, but that is the only place the leak is.
(https://i.imgur.com/aqx8j98.jpg)
(https://i.imgur.com/wtXWLn6.jpg)
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Take a pic of where the leak is and we can advise on the usual suspects, it's too vague saying it just leaks, there are a number of areas prone to leakage and we need to isolate where it's coming from.
Just uploaded two pics. It leaks in each end, making me think maybe its leaking from the o-ring on each side of the engine. But I am not sure if it can be anything else. Any advice is greatly appreciated!
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Are you sure its not the end cap O rings that are leaking? they are very, very prone to it.
Just uploaded two pics - one of each side. It seems like its the o-rings that are in each side of the motor. What do you think?
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I can't see a lot from your pictures -It's a long shot but an easy fix - are you sure you have good venting from the top of the engine a bit too much crankcase pressure can push oil out at the easiest places. Sorry if you have checked that.
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No expert on the 500/550 engine having only rebuilt one engine but from memory, if the 550 is like the 500, doesn't the (handed) cam cover end cap 'L' brackets (that the end cap screws to) have copper sealing washers on the bolts that are sometimes mistakenly get replaced with ordinary washers? Could it be that?
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It's the oil gallery O-Rings, most likely because aftermarket head gaskets are thicker than Honda ones and they don't appear to make the O-rings they supply thicker to compensate for that, so they crush like they should and end up leaking.
OE gasket will solve it unless there is some damage to the surface but then why both ends at the same time?
Thank you for this advice. Sorry for a potentially stupid question (English not being my first language), but what does OE mean? That the gasket follows the original factory specs? Or?
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Honda gaskets are thicker as well its all due to no asbestos. Two gaskets in that short order i would check head and block for flatness and that correct length dowels between head and block are used
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Same part number Ken
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Either way I wonder if it’s worth trying slightly over sized quality o rings as an additional precaution?
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I went round the houses trying to fix the same problem and got very frustrated.
As Trig says there is an issue with the thickness difference between aftermarket head gaskets and OE ones.
I finally cured mine by……….
1 Using an OE gasket (DSS can supply)
2 Having the head skimmed to ensure it was flat
Since I did the above no probs at all.
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I already made sure the head was flat. So an OE set from David Silver or thicker o-rings. Does anyone have a source for usable o-rings. This will be the third time taking the top apart. Would really like to get it right this time!
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Try Nurse Julie on here who stocks a wide range of quality O Rings
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I know posted somewhere are the O ring sizes cos i did it but im at work so cant look in my very old parts book to tell you, then just google an o ring slightly thicker section
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5 x 2.4 according to the Parts book in Aladdin's Cave on here.
I used a slightly bigger thickness Viton O rings on my CB550K2, with an aftermarket head gasket from David Silvers, and it never leaked again.
Hope this helps,
Brian.
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5 x 2.4 according to the Parts book in Aladdin's Cave on here.
I used a slightly bigger thickness Viton O rings on my CB550K2, with an aftermarket head gasket from David Silvers, and it never leaked again.
Hope this helps,
Brian.
How many km since?
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5 x 2.4 according to the Parts book in Aladdin's Cave on here.
I used a slightly bigger thickness Viton O rings on my CB550K2, with an aftermarket head gasket from David Silvers, and it never leaked again.
Hope this helps,
Brian.
How many km since?
After doing the work I did about 2400 miles up until I sold it, I think that'd equate to about 3700 km.
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Julie’s set of 5 o rings sorted my oil pump. Bone dry now👍
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5 x 2.4 according to the Parts book in Aladdin's Cave on here.
I used a slightly bigger thickness Viton O rings on my CB550K2, with an aftermarket head gasket from David Silvers, and it never leaked again.
Hope this helps,
Brian.
Hey Brian
So you used a slightly thicker version than the 5x2.4? Or did you use the actual 5x2.4 sizes?
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No, as per advice from here it was definitely thicker than the 2.4 in the parts book. After I bought my O-rings from Seal Supplies of Loughborough via Ebay (I bought various ones, not just those) I saw that Nurse Julie on here stocks and supplies O-rings, it's probably a good idea to see what she has to say on the subject.
I don't have the receipt for the O-rings I bought, but it would have been one size up I'd say. And I bought some in Nitrile and some in Viton.
I hope this helps!
Brian.
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Further to the above, I've been through my Ebay purchase history at my O-ring purchases. Based on the Honda standard thickness of 2.4 and what I bought around that time, they would either have been 2.5mm Viton (which I doubt because it's hardly any thicker at all) or 3.0mm Viton. I'd say it's 99% definite that I used 3.0mm, which makes sense to me today as a proper thickness upgrade. And mine definitely didn't leak again up to when I sold it.
But, you would be far better advised by Nurse Julie's experience than my recollections!
I hope this helps.
Brian.
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Further to the above, I've been through my Ebay purchase history at my O-ring purchases. Based on the Honda standard thickness of 2.4 and what I bought around that time, they would either have been 2.5mm Viton (which I doubt because it's hardly any thicker at all) or 3.0mm Viton. I'd say it's 99% definite that I used 3.0mm, which makes sense to me today as a proper thickness upgrade. And mine definitely didn't leak again up to when I sold it.
But, you would be far better advised by Nurse Julie's experience than my recollections!
I hope this helps.
Brian.
Thank you Brian! I've written Julie on here in a PM, so hopefully I will hear from her soon :)
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Just a quick update question: Since I've just changed the entire gasket set for the top engine, can I take it apart and only substitute the O-rings, or do I have to substitute the whole thing when I take it apart??
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Depends on if it was an originaly sticky gasket and does not rip when you take the head off also only if it hasnt been run
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It definitely has run!
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Then you definately need a new gasket