Swap to a 12 volt coil, and add a ballast resistor between the battery and the coil for extended running time, and you should be able to run it indefinitely without problems. You might have to jumper around the resistor for startup, but not unless it has trouble getting going without the bypass. The starter will work great on 12 volts- - - -just don't crank it for long periods of time.
Jerry


"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!