went to the track two weeks ago and while powering thru the whoops when i came out the throttle stayed open,i hit the kill switch brought it home. during the week i checked the cable theres no bind its routed properly, i pulled the carb and checked the slide, there was no wear and it was clean.put it back together yesterday and went to the track,made about four laps when powering up a tabletop it happened again,only this time it hurt,collapsed lung fractured ribs and seperated shoulder, when a 500 verses trees and rocks outside the track,trees and rocks win,i couldn't kick the bike away or find the kill switch, any idears as to whats happening??? the throttles free it only happens while riding ??[/b]