i was riding my 86 350x yesterday and it was running great and then it started making a sound like the chain slapping. All of a sudden it locked up and died. I can't kick the bike over, and the kick start won't even budge. I drained the oil, no metal, oil looks good, what could it be? Please help. BTW, just had the motor rebuilt 6 months ago. All the gears are working great, it goes through all the gears, Im baffled, I need input ASAP.... Thanks, Steve