Hi guys,my 400 motor was completed today, has std Wiseco piston kit, head rebuilt by Eric Gorr, 2003 yz450 Cam mod , ngk CR8E plug and using 2000 WR Exhaust. Started after couple kicks for first time with choke out. I allowed it to warm up and pushed choke in and it stalled. Restarted easily and i played with throttle a bit allowing it to run a bit over idle rpm, then after about 5 mins i noticed the head pipe was starting to glow so i turned motor off right away. Any ideas what this could be ?