Oil around left side spark plug

[Johnny3D]

One of the things I discovered during my initial inspection of my 1980 XS400GS is that it has a relatively small amount of what looks like oil coming out from the left side spark plug. Any ideas on what could be causing this and how I would go about fixing it?

 

[Wolfe_11B]

Is that bolt missing under the plug?

 

[Johnny3D]

No, the bolt is there and the oil isn't coming out from around that bolt. The oil seems to be all around the spark plug itself. I haven't pulled the plug yet since I figured I would see if you guys knew what I might need to fix it before I take it out.

 

[Wolfe_11B]

Well I'm sure it's not coming from the plug hole. If there is oil coming from there, then you've got some issues to deal with!

It's either coming from the seal on the cam sensor, or its leaking from the valve cover and pooling there.

 

[Johnny3D]

Well... I decided to pull the plug and have a look at it and try and get a better idea of what is going on there.

First thing I noticed was a fair amount of grit/grime on the plug itself when I took it out. Also the plug is obviously oil fouled.

There was also quite a bit of grime/dirt around where the plug should seal.

While I was cleaning up the grime from the plug area, I smelled some of the soot and it smelled distinctly of gas. I cleaned up the plug as well then re-seated it. Engine still seems to be running just fine.

My guess is that the plug did not have a good seal to the engine and that a tiny bit of the gas vapors were escaping and collecting just outside the plug, making a bit of a mess. Hopefully the cleaning of it will help take care that and there will be less mess around that plug.

So... the fouled plug. From what I read it could be an improperly adjusted carb, worn piston rings or valve seals. Aside from disassembling the engine and inspecting it, is there any way to check which one of those it might be?