oil on spark plugs - valve seals?

[salindroth]

1975 R90/6

I noticed oil on the left spark plug threads. The bike runs smooth, starts up fine, the power is good, and no blue or white smoke, so I don't think the rings are worn.

A friend suggested valve seals. I can't find these seals as a separate part. I realize the R90/6 does not come with valve seals.

Would replacing the valve guides and valves fix this issue? Thanks for any advice!

 

[PGlaves]

1975 R90/6

I noticed oil on the left spark plug threads. The bike runs smooth, starts up fine, the power is good, and no blue or white smoke, so I don't think the rings are worn.

A friend suggested valve seals. I can't find these seals as a separate part. I realize the R90/6 does not come with valve seals.

Would replacing the valve guides and valves fix this issue? Thanks for any advice!

Do a leak down test. If valves are found to be culprits then yes. Otherwise no. And I will add if it runs well and doesn't consume much oil you are chasing a perfection which doesn't exist in air cooled engines.

 

[salindroth]

And I will add if it runs well and doesn't consume much oil you are chasing a perfection which doesn't exist in air cooled engines.

Much appreciated. Thanks.