Background: bike overheated and dropped a valve in original head and trashed it. So three weeks ago I did a complete to end rebuild. Bike sat for about 6 months while a got all the new parts together. New ported race head, new piston, rings, got cylinder honed, gasktets ect. Did alk the work my self shimmed valves in specs timed ignition started right up. I Broke it in how everyone on here said to do in heat cycles. Ran like a new bike. Did two local races last few weeks bike ran great no problems what so ever. Yesterday took it out for a friday practice. She ran great all afternoon. Then took a break and was gonna do a 5 lap practice race. 4th lap in I went into a turn hot and she started to bog and sputter then stalled. Waited a few minutes then she fired back up but didnt want to keep running. So I kept the rpms up and feathered it back to the truck. Got back let her sit for a few minutes to cool down while I got some water. About 10 mins later got back on started her up rode great for 2 laps then again same symptoms. Bogging then stalled. Frustrated I kicked and kicked then using the hot start she fired back up took her back to the truck and loaded her up. That evening I tore her down and cleaned out the carb and checked valve clearance. Still all in spec. And looking good. Buttoned her back up and fired her up with choke out. Ran good for few minutes then died as if kill switch was hit. Played with fuel screw still same start then die out. Checked gas tank vent hose...all good. Cracked open gas cap still start then die. Could the stator or cdi of gone bad just like that? Is it a bad rod bearing? Im hoping not that after everything ive put into the top end. Please help!!