i was riding my 450r yesterday when it just cut off after that i rolled it off and it started and ran for a min. and cut off. i tried to kick start it but the kick would not move. a buddy kicked it hard as he could and it moved and started ran for a second and then just cut off. we tried pulling it off and it would not even try to start. i took the seat off and found out that the screws had broke off the K&N filter and it was sitting in the bottom of the air box. i went threw alot of mudd and im sure it got some in the motor. do yall know the best, cheapest way out of this problem?

 

I think you are going to have to tear into it and look at it. Start with the intake boot and the carb. If they have dirt in them, you know it probably got into the combustion chamber.

I wouldn't keep trying to start it or anything like that. A bunch of dirt in your combustion chamber is just going to do lots of harm...best if that piston doesn't move.

 

Are all the screws and nuts accounted for?

If one went through the intake...