electrical

ok went to the track yesterday rode one warm up lap and rolled over everything and then 1 more lap and proceded to hit some of the doubles and the table top, then just as im coming around the turm to start my third, my bike dies, so i start it and it runs for maybe 5 seconds then dies and wont start, so i roll it off the track and proceed to tear my bike apart in the back of my truck, filter is brand new, its got compression, its got gas, changed the plug, but after i changed it i still had no spark ( i even stuck a screwdriver in there and held on to it while my friend kicked the bike over, so one of the older riders there checks it out for me (i have no clue about anything electrical) and says it may be my ignition coil, but what do you guys think and what will all this cost

p.s. i can start my bike after it cools off but it only runs for maybe 9-10 seconds before dying