Topic: Cb350f ring help

[innovativems]

Evening

So I have A 72 cb350f that was running well and I rebuilt the top end while it was getting redone.  It ran well and didn’t smoke before the rebuild. The head was sent to the machine shop and new valve guide seals, and a valve job were done and I gone the cylinders and found some nos standard piston rings to re ring it. Gapped them to specs and the bike smokes like a two stroke.  When I installed the rings, there were no markings on the oil rings to identify the top of them. 

Fired the bike up and it smoked like a two stroke.  White smoke with oil residue coming out all four head pipes. 

From what I measure, I don’t see a different in the orientation of the oil ring.  Any thoughts would be great.  Thanks!


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[innovativems]

i guess my biggest question is, on the one piece oil ring, does it matter which side is up?  I don't see any markings anywhere on the rings, used a light and magnifying glass

[Bodi]

The oil ring is rarely a problem but if you can see an angle on the outer edge of the contact surfaces that should be oriented so it scrapes oil down. The usual problem with a smoker is the second ring, this will definitely have the outer face angled and that must scrape down - upside down it scrapes oil up into the combustion chamber area. The compression ring (top ring) has square cut edges.
If that's all good... ?? Valveguide seals? Worn guides and/or valvestems?
Even a freshly rebuilt engine, although it will smoke a bit until the rings seat, shouldn't leave a smokescreen.

[camshaft1991]

Where did you get your rings? The indicators for which side is up are usually small arrows/triangles near the ring gaps. I can’t find a pic but here’s a simple diagram on ring placement.

The scraper, in the middle, is the only one you can position without an indicator. Maybe someone can post a pick of what I’m taking about with the indicator arrows/triangles. When you pull your engine, feel that middle ring with your finger. Push the gap side of the ring in so that back side pokes out. If the sharp edge of the ring is facing up, then it’s upside down.
Also post pics and videos if possible.


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[innovativems]

Well I’m feel dumb.  Middle ring was upside down on all four.  These are now Honda rings from who know how long ago and only had markings on the top rings.  Thanks everyone!


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