Was riding my 450, testing out a new speedometer, shifted into 2nd, moved a couple feet and heard a loud crack noise from engine area. Will not turn over, sounds like its jammed or seized from moving. My guess is tat the timing chain just exploded and fouled everything up. Haven't found time to open it up. Thought I'd go to forums to get some opinions on what to look at first. As far as back round info: Engine was opened up to replace some gaskets. replaced my valves and adjusted rockers to .05mm. Timing chain taken apart a couple times. Shifts through gears fine even though it doesn't run. I am not very fond of ktms or dirt bikes in general but fairly mechanically inclined. I don't know what to do so here I am on the forums. Any help or advice is much appreciated. Thank you.