ok i started up my 2000 beartracker 250 and rode it like 100ft then put it into neutral and was revvin it up. i was revvin kinda high when all of a sudden it kicked into 3rd or 4th gear. so i kicked it back into neutral (or so i thought) then shifted up one so id be in1st to take off. well it stayed in 3-4. so i took off and went to shift and my back wheels locked up. so now ALL i have is 3or 4th. any ideas on what might be wrong? THANKS