Last time i had that kind of starting issuse with my 54 3100,it was the coil. Start good cold, no start hot, coil was hot to touch.i think once i poured water over it to cool it down to start. It was still 6v at that time too. When it doesnt start,pull a plug wire off and have someone crank the engine over.hold the wire close to the engine or a bolt and see if you have a spark jumping to ground. Oh, use insulated pliers to hold the ing lead. If you do have spark you will feel it !
