Oily spark plug

[JoeP]

Hi all. I pulled the plug from the vertical cylinder and noticed there was black oily stuff all over the threads and around the tip. Quite a bit of it. No oil above the threads and inside the spark plug tube. What gives? Could the oil be unburnt fuel from running really rich? Plug only has 1K miles on it.

[ducpainter]

Any chance you can take a pic?

[JoeP]

Any chance you can take a pic?

I wish I thought of that, but I cleaned it up already. Black and oily is all I can describe it as-- from halfway up the threads all the way to the spark gap. After I wiped it off, the plug looked normal. The other plug looked fine.

[ducpainter]

Carby or injected?

It could be fuel, or oil. Hard to say.

[JoeP]

Carby or injected?

injected

[ducpainter]

If it continues, take a pic.

It's possible it could be a dirty/leaking injector, or it could be a bad valve guide seal, or a coil issue, or simply a bad plug.

You might switch the plugs to see if the problem swaps cylinders.

[JoeP]

If it continues, take a pic.

It's possible it could be a dirty/leaking injector, or it could be a bad valve guide seal, or a coil issue, or simply a bad plug.

You might switch the plugs to see if the problem swaps cylinders.

Thanks! In addition, I just measured my valve clearances and found that they're way out of wack. Intake closer clearances are much too large (both intake and exhaust) and openers are too small (exhaust). I'll fix that first and then keep an eye on the spark plug as you suggested.

[desmodoktor]

Any chance you can take a pic?

He's got the same issue I have ... I'm thinking It's a bad valve seal...
By looking at the pics I've posted u can tell that there's oil going in the combustion chamber somehow.. there's no black smoke coming out ,and the oil level is not going.down ... so I think there's a little oil coming in mixing with gas .. I'll try to replace the valve seals if I can since both my heads r out .. and see how it goes ...

[desmodoktor]

I wish I thought of that, but I cleaned it up already. Black and oily is all I can describe it as-- from halfway up the threads all the way to the spark gap. After I wiped it off, the plug looked normal. The other plug looked fine.

Does it look similar to this?

[JoeP]

Does it look similar to this?

Yes but much worse. The oily stuff was almost dripping off the plug.

[desmodoktor]

Yes but much worse. The oily stuff was almost dripping off the plug.

Oh... Let me go home and check on those valve seals and o rings and I'll probably post a picture if i see Smth related to that ....

[desmodoktor]

hey.. sorry for the delay !

so here are few pictures of my horizontal cylinder...


inlet Valve . (looks pretty clean)





exhaust valve. (looks dirty and oily)





and this is how the valves look like


the dirtiest spark plug is from the same cylinder.



so from my understanding it look like oil is passing through and its burning there...
inspected the valve seals and one of them (on the exhaust side) has a little cut on the top. the valve rods measured OK. so signs of wear there*
planning to replace all valve seals .
i say open up ur valve covers and inspect the seals carefully , see if there's any sign of wear or cuts/damage...

[JoeP]

Thanks! I'll check the valve seals. Can they be replaced without pulling the valves out?

[desmodoktor]

here are some pictures of my horizontal cylinders valve seals ... the green one is the exhaust valve seal , the black one is the inlet valve seal.
as you can see the exhaust valve seal is pretty beat up and worn .. (slid them to the valves and moved them up and down to test how much they were worn. so the green valve seal was moving  up and down pretty easy compared to the black valve seal ) i will replace them all .. everything is open anyway .

[desmodoktor]

Thanks! I'll check the valve seals. Can they be replaced without pulling the valves out?

i dont think so ... the rocker arm is on the way .. i mean u can but u will have to force it out through the rocker arm ... (i wouldn't risk damaging the new valve seal )