has anyone heard of this, I was at the track and about to kick start my bike but it seemed like the motor was locked up, the de-compression would not free it up so I put it in gear and rocked it backwards and then I was able to start it up. After a couple of laps it started making a bad knocking clackity sound. I shut it down and went home and fired it again and it made the same noise, I revved it up and it clanked hard and stalled the motor. I pulled the top cover and the valves are ok. It will turn over now but sometimes locks up and I have to reverse the motor to get it spinning again. I have the motor out of the bike but not sure what to do next?