Spark plug got oil on the thread...

[gazza]

Wonder if anyone could shed some light on this...

I decided to check my spark plugs as I'm about to change the oil and filters etc only the left hand side front spark plug has got oil on the thread (I'm guessing it would be all over the tip but has been burt off?)
There's no oil in the spark plug tube or visible leaks.
The tip of the plug looked all coated like rich mixture so I check the right hand side spark plug, but it was fine looked normal.
So the oil seems to look like it's just in the thread of that spark plug hole.

I know the spark plug was clean when I put it in there last year.
I'll put new plugs in and probably spray some carb cleaner down there and carry on like it never happened but just wondered if anyone had any ideas?

Thanks.

[VulcanE]

How many miles on the bike? Do you know if it has ever had cam chain tensioner extenders installed? The spark plug tube on the front left is removable, and if the cam chain gets too much slop in it, the chain will wear a hole thru the spark plug tube and then you'll get oil in on the top outside of the plug. You might want to remove the tube to inspect it.

[AlabamaNomadRider]

How many miles on the bike? How many on the plugs? I would check for damage on the spark plug tube like VulcanE mentioned.

[ringadingh]

You should use anti seize on the plugs when you install them, or they will seize in and become very difficult to remove over time.

[gazza]

Originally Posted by VulcanE

How many miles on the bike? Do you know if it has ever had cam chain tensioner extenders installed? The spark plug tube on the front left is removable, and if the cam chain gets too much slop in it, the chain will wear a hole thru the spark plug tube and then you'll get oil in on the top outside of the plug. You might want to remove the tube to inspect it.

Thanks for the replies.

The bike had 6k miles when I bought it now it's got 26k miles on so no tensioner extenders fitted but the oil isn't on the outside, it's only on the thread as it screws into the cylinder so it looks like it's in the cyclinder itself. I'll pop the tube out and have a look though to be safe.

[gazza]

Here's a pic. The outside of the plug was clean. The thread and tip look dreadful.
The plug the other side (same cylinder) was fine and dandy.



The oil looks like it's just on/in the thread.

[macmac]

I think that plug was slightly loose The crush washer isn't fully crushed, and then the threads are not seals so fuel some oil and carbons ran up the gap in the treads. Threads do not fill the whole space beteen the nut wall side and the bolt wall side, not even close.

I know this is a plug, but the threads are alike, and there is air space between a bolt locked in a nut.

If it were me I would clean the head side threads with carb cleaner, and not be all that fussy maybe stuff in a lint free blue paper towel to mop up the mung.

With this many miles on original plugs you are in the ball park to replace them.

Or if yer as cheap as me file the electorde square, then clean the inner plugs areas by setting them on a brick and 'painting' them with a propane torch to burn off the carbon.

If you do that wait a long time before you tough a plug as that ceramic hold Damn HOT a long time.

Then anti seize just the plug threads, and not any of the electrodes. I know a guy who about swam the plugs in the bottle, lets just say that didn't work very well.

Then in say 3,000 miles pull the offender and see if the anti seize is all black.

I think compression, a too big a gap, but not to big for capillary action, made that 'varnish' which is only a little part real oil.

And while your right there, pull the rubbers off the plug end resistors and get the green mung off the internal brass parts, just watch out for the very small hair pin spring in there. Don't lose those. They should not be free to fall out, but sometimes they still do.

[gazza]

Originally Posted by macmac

I think that plug was slightly loose The crush washer isn't fully crushed, and then the threads are not seals so fuel some oil and carbons ran up the gap in the treads. Threads do not fill the whole space beteen the nut wall side and the bolt wall side, not even close.

I know this is a plug, but the threads are alike, and there is air space between a bolt locked in a nut.

If it were me I would clean the head side threads with carb cleaner, and not be all that fussy maybe stuff in a lint free blue paper towel to mop up the mung.

With this many miles on original plugs you are in the ball park to replace them.

Or if yer as cheap as me file the electorde square, then clean the inner plugs areas by setting them on a brick and 'painting' them with a propane torch to burn off the carbon.

If you do that wait a long time before you tough a plug as that ceramic hold Damn HOT a long time.

Then anti seize just the plug threads, and not any of the electrodes. I know a guy who about swam the plugs in the bottle, lets just say that didn't work very well.

Then in say 3,000 miles pull the offender and see if the anti seize is all black.

I think compression, a too big a gap, but not to big for capillary action, made that 'varnish' which is only a little part real oil.

And while your right there, pull the rubbers off the plug end resistors and get the green mung off the internal brass parts, just watch out for the very small hair pin spring in there. Don't lose those. They should not be free to fall out, but sometimes they still do.

Thanks Macmac. Great advice and that makes sense because the oil was only in the threaded hole.
I've got myself some new plugs coming via ebay (too lazy to mess about with these ones!)

Thanks once again :)

[macmac]

Nice clear pic helps a lot.........