Spark plug insulator tip broke?
#6
I'd check compression on that cylinder. Could be that a broken ring-land hit & broke it...or something damage related in the area of the combustion chamber.
Could be leaky valve stem seal, damaged valve, piston, rings...
Sounds like you'll be pulling the head.
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#8
Had this happened twice to a race motorcycle we had a few years back,dismissed this as a bad plug. Found out it was preignition after it had nawed the front of the piston above the rings on a tear down.
Its possible its happening to you too. Hope this helps.
Good luck...
Its possible its happening to you too. Hope this helps.
Good luck...