Originally Posted by nigelcorn
Yeah, I'd planned on putting a new plug in. I'll see what's going on with the jetting. I haven't seen a lot of spark plugs before so I don't have much experience, but this does seem to have a lot more carbon build-up than the others I've seen.
I really hope it isn't burning oil, I've already had to deal with one bike burning oil that turned into a nightmare.
That one is worn out and it looks like it wasn't fully tight, close, but not fully...that's why the threads are black.
Check for a stuck open thermostat, it will make the engine run too cool and cause carbon buildup about like that.