Chris,
I have a ’86 Kawasaki Vulcan 750 that acts that way when the battery does not have a full charge. Apparently, the stator does not put out enough current, when the starter motor is cranking the engine, so it needs a well charged battery to supply the additional current to get that blue spark out of the sparkplug. I believe you might have a defective battery, stator/generator, or both. Check the voltage regulator too once you get the bike running. The next thing I would do is to jumper cable the bike to a not running/started vehicle and see if it will start and stay running with the extra current from the vehicle. If it starts and stays running it might just need the battery charged up or replaced. With the bike still running, disconnect the jumper cables and see what happens. If it stays running it’s probably just a battery/voltage regulator problem. Check stator and voltage regulator output. If it stops running or only runs for a little while, it’s probably a bad stator. On my Kawasaki, I replaced the battery, stator and voltage regulator, problem solved. I am not a motorcycle mechanic, I have stayed at a Holiday Inn … so, good luck. Arp