Motorcycle Repair: 97 sportster, gas flow, plug wires

Question
i had the bike tank painted, after that the bike will run for 20 or 30 min then die as if it ran out of gas. let it sit for 15 min or so and it will start and run fine for another 20 or 30 min then quit again.i first thought somthing got into the tank and in to the carb but im not so sure.when it acks up it will run rough like only one cylinder is fireing then none.wait a while and everything is fine.my son was riding the other day and when it quit on him he checked for spark and found none at first and after a while the spark seamed to return and the bike restarted.when it quits i never smell gas like it is flooding when trying to restart so i thought it was a fuel probiblem at first but now im not sure. thank you   william jackson  

Answer
First, I would start by making sure you have a good gas flow. Remove the hose from the carb and check there. Next, mkse sure you have a good spark. Since you stated that there was no spark after riding it, you need to test the coil and plug wires. Coil can fail when they get hot. So test it cold and then put it in a over to heat it up and test it. If they test fine then you ignition is probably getting ready to go out.
Mike