Whats you thoughts on this situation ?

[blue02banshee]

Hi, i have an 02 Banshee with mildy ported cylinders, one-over pistons, all the standard bolt-ons including +4 timing, DMC pipes. I was in the process of jetting the bike and had just put in some 330 mains. I was warming it up and all of a sudden the motor started to knock and died, upon restarting it it wouldnt idle or stay on with more throttle and obviously was still knocking heavly. The motor was running very strong before but to be safe i threw in some bigger mains, i have had no problems with it before this all happend. I pulled the motor out right-away not cause any further damage. Before i took the cyclinders off i had the crank cover off and when i spun the crank backwards in would jamb-up. It would spin freely in the right direction (is this normal i had never seen this before). One of the piston did seem to be to-tight when it reached the bottom of the cyclinder when i was pulling the cylinders off. Thanks