Big problem?

[dirtbike&quad]

was riding my friends blaster in this technical section he couldnt do in the woods and i put it into neutral for him and just start to rev it and without giving it any gas it just REVS SO HIGH like it is full throttle even if ur not on the gas and it wouldnt stop even if we turned the gas off or turned the key. it just died down but it restarted. then later it wouldnt start up. we gave it a rolling start and started it up but then it did the revving thing it just sounded like it was pinned and it wasnt at all..

long post sorry but confused!

[YZ400EX]

I could be that the slide in the carb is stuck in the open position.. it could be the needle in the slide is not dropping with the slide.. it could also just be the throttle cable is stuck at WOT and just the spring in the thumb throttle housing is working making you think the cable is moving.. check the cable first, then the slide.. When you are hitting the throttle with it turned off can you hear the slide moving?? can you hear it drop in the carb??