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rYan01400EX
06-27-2006, 08:37 PM
Alright guys, been a while since I've stopped in. Well, to the problem.. I was riding my 400EX the other day and all of a sudden I hear a slight ticking... then all of a sudden boom.. It blew the spark plug out of the head and blew all the pieces out of the spark plug cap. I think it was due to preignition... I am not a hundred percent positive.. Help appreciated.
RiderTRX400ex
06-27-2006, 08:43 PM
did the plug just come loose? if you turn it over without the plug in does it sound normal? are the threads for the sparkplug still good?

let us know
rYan01400EX
06-28-2006, 09:57 AM
Yes, the spark plug came loose. BUT, threads in the head are fine and the spark plug will rethread back into the head. When the wire came apart (the boot) I'm not sure how it goes back together. I took the head off just to ensure no problems with the the threads.. I think maybe it overheated and the head expanded just enough to let the spark plug blow out. If thats the case, I don't know what would cause it to overheat.