sr250 help

Hello all, I have an 81 sr250 that I've run into some problems with, I recently replaced all the gaskets and o-rings in the engine to stop an oil leak which was successful and after doing all of that I rode it around town problem free for a couple hours and later on in the day the throttle would stop having any effect and the engine would cut out. After going through this a few times finally getting it back home I took the spark plug out to find out it wasn't getting any spark, I got a new flasher relay which didn't seem to solve the problem and now am waiting to recieve a new ignition coil, my question is if anyone knows what the problem could be if not the ignition coil and if anyone could help. Thanks!