200EXC won't start: clattering noise

[Wackob0b]

I was riding my bike yesterday when my bike revved without my input at 3/4 throttle and then the engine died. I tried starting it several times but was unable to and the engine made a clattering/cranking noise. What is wrong?

I also noticed the engine or exhaust noise, I'm not sure which, sounded excessively loud. It was a sort of a high pitched ring almost sounding like an exhaust leak but it wasn't very distinct. I don't know if this has anything to do with the problems as it wasn't consistent all the time.

[AJ_YFZ]

Welcome to... might be time for a new topend

[Wackob0b]

There was no loss of power or any symptoms before this happened. I even had the bike being serviced at the local dealer. It doesn't need a new top end. What irks me is the cranking noise and failing to start.

[Cr250NICK]

I had something similar happen to my bike, was riding hard, then the note/sound of the bike changed completely, then 5 seconds later it died and would not start. Took the head and barrel off and part of the piston had blown apart and went through the rest of the engine! costly mistake for leaving a piston in to long!!!

I would take the head of immediately before you try starting it again!