Cb550F continued oil leak. Nature of the beast?

[alexdecker]

Hey all

So went through the entire engine last year. The works. Also measured the flatness of the cylinder block and head. It is within spec. Obviously also changed just about every gasket and seal in the engine. That included a Vesrah gasket kit for the top end. I also substituted the oil gallery O-rings for someone slightly thicker (as per this forums suggestions). Got it back together. Ran it. No leaks.

Changed the oil in November and stored it over the winter. And now the leak is back. From that damn left oil gallery between cylinder and head. It is a lot less though. Even with and hour on the freeway, it doesn't leak bad enough to drizzle on my shoes or any of the bike in general.

Is this oil leak just something CB550 owners have to live with? I heard that Honda didn't include enough bolts in the design to properly tighten down the top end. And I feel like I've done pretty much anything that can be done to stop it (with the exception of using liquid sealant around the oil galleries. But maybe a little blue Hylomar would do the trick?).

Can this oil leak be stopped in general? Or should I just ride and have fun with it, and appreciate the fact that at least I don't have to buy new shoes all the time 

[deltarider]

My CB500 sweated oil when I bought it April 1980. The head has been of twice and - in spite of promises made by the mechanics - it still sweats oil. As long as it doesn't dirty my clothes, I can live with it.

[Trigger]

If you used the o'rings from the Vesrah gasket set, they will leak. Vesrah's gaskets are thicker than the original Honda ones but, vesrah just took the Honda sizes to make up the o'ring for the gasket sets so, they are too small and you don't get a good seal. Also a lot of Honda o'rings listed in manuals must have been translated wrong and are not the correct size.

I think James Harrington has had problems with some oils that leak and others don't ,if i remember correctly. 

[Oddjob]

There is a solution, it's radical but it would work, however it does detract from the look of the engine somewhat.

Far easier to try and see if it can be fixed without resorting to that. My advice would be to buy a genuine head gasket, a genuine topend set is best. Ok it's not cheap but you're in Europe and they tend to be cheaper over there as a rule. You could also think about fitting a copper head gasket and get an O-Ring to suit how thick that is. I did measure the difference between an aftermarket head gasket and a genuine one and there is some difference, saying that would the manufacturers have known this and substituted thicker orings to suit? Must check those and see. As for translation errors in the parts book, yep they do happen, words though, not numbers, numbers are sort of universal, 1 is 1 in any language, doesn't matter if you have to translate it, everyone on the planet knows what 1 stands for.

[alexdecker]

Ah, but I upsized the O-ring from 2.4 to 2.5 as per Julies advice. I do believe that is why it leaks somewhat less than it did before. But I guess it was not completely enough.

Maybe a genuine gasket set and upsized O-rings would do the trick? Or should I use the proper sized O-rings when using a genuine gasket set?

Also - where do I actually get a genuine gasket set? CMS seems to carry a million options, and Im not really sure if any of them is genuine Honda?

Ken, I'd love to know what drastic methods you are talking about?

[Oddjob]

The problem as I see it in upscaling the thickness of the oring is the head gasket itself, if you make the oring thicker in section and get it wrong it either doesn't seal OR you go too much like 2.6 and that's too much. No problem you think, it will just crush down, which is true but it can only crush down into the space allowed for by the hole in the head gasket, once it reaches the capacity of the hole in the gasket the ring can't go anymore unless it actually starts to split the gasket to make room. Personally I'd say if you increase the section decrease the diameter a little, maybe 2.3 x 1.6 would have been a better choice, just a theory of mine.

If using genuine Honda gasket kit use the orings provided, you need part number 06110-323-000 for a 500, 06110-390-000 I'd imagine for a 550. Head kits always seem to be 06110 then model number, then normally 000, base kits are 06111 IIRC.

Sorry forgot to mention the radical method. Only seen this done once BUT it does work. You get an adapter plug to fit into the blanking plugs that are fitted in the crankcase to seal off the crankshaft oilway. Something like this https://www.ebay.co.uk/itm/175599841260?_trkparms=amclksrc%3DITM%26aid%3D777008%26algo%3DPERSONAL.TOPIC%26ao%3D1%26asc%3D20220705100511%26meid%3Db1593f3ab8b94c05bfa779451747f9e3%26pid%3D101524%26rk%3D1%26rkt%3D1%26itm%3D175599841260%26pmt%3D0%26noa%3D1%26pg%3D2380057%26algv%3DRecentlyViewedItemsV2&_trksid=p2380057.c101524.m146925&_trkparms=pageci%3A1f8ed881-1113-11ee-b766-b2c78a803bab%7Cparentrq%3Ae3c3afb91880ab8f4e980403ffff6196%7Ciid%3A1

You then run a pipe outside the engine up to the blanking plug fitted to the head just under the camshaft end caps, drill and tap that to suit the new pipe and you've now effectively bypassed the entire oilway that's causing you the problems, blank that off and run the oil outside of the engine to the cam. The version I saw used hard lines not something like braided lines, much neater and smaller. Radical but effective.

[alexdecker]

The problem as I see it in upscaling the thickness of the oring is the head gasket itself, if you make the oring thicker in section and get it wrong it either doesn't seal OR you go too much like 2.6 and that's too much. No problem you think, it will just crush down, which is true but it can only crush down into the space allowed for by the hole in the head gasket, once it reaches the capacity of the hole in the gasket the ring can't go anymore unless it actually starts to split the gasket to make room. Personally I'd say if you increase the section decrease the diameter a little, maybe 2.3 x 1.6 would have been a better choice, just a theory of mine.

If using genuine Honda gasket kit use the orings provided, you need part number 06110-323-000 for a 500, 06110-390-000 I'd imagine for a 550. Head kits always seem to be 06110 then model number, then normally 000, base kits are 06111 IIRC.

Sorry forgot to mention the radical method. Only seen this done once BUT it does work. You get an adapter plug to fit into the blanking plugs that are fitted in the crankcase to seal off the crankshaft oilway. Something like this https://www.ebay.co.uk/itm/175599841260?_trkparms=amclksrc%3DITM%26aid%3D777008%26algo%3DPERSONAL.TOPIC%26ao%3D1%26asc%3D20220705100511%26meid%3Db1593f3ab8b94c05bfa779451747f9e3%26pid%3D101524%26rk%3D1%26rkt%3D1%26itm%3D175599841260%26pmt%3D0%26noa%3D1%26pg%3D2380057%26algv%3DRecentlyViewedItemsV2&_trksid=p2380057.c101524.m146925&_trkparms=pageci%3A1f8ed881-1113-11ee-b766-b2c78a803bab%7Cparentrq%3Ae3c3afb91880ab8f4e980403ffff6196%7Ciid%3A1

You then run a pipe outside the engine up to the blanking plug fitted to the head just under the camshaft end caps, drill and tap that to suit the new pipe and you've now effectively bypassed the entire oilway that's causing you the problems, blank that off and run the oil outside of the engine to the cam. The version I saw used hard lines not something like braided lines, much neater and smaller. Radical but effective.

That's is a little too radical for me But interesting!

I used Veton 5x2.5, and the manual says to use 5x2.4, so only upsized 0.1. Alas, still a bother. Will try and source a genuine kit. Gotta have something to do come winter