to open the magneto you need a piston stop to stop the stroke of the engine. a regular 3/8 drive ratchet will fit in the nut on there. the nut is reverse threaded so you have to tighten it to loosen it. before you go crazyin the electrical system, do you have spark? have you checked it by pulling the spark plug, touching the engine with it and cranking the bike? i would check ground connedtions before jumping into the electrical stuff. you should have a braided wire that runs from your high coil to your engine mounts. also check the grounds at the zenor diode (the heat sink under the headlight). if your zenor went bad you could have blown the condensor. the zenor diode is the voltage regulator for your bike and without it on a 6 volt system (anything pre '78) you will fry condensors all day long. also you want to disconnect your kill switch. you can do this by disconnecting the jumper wire that is on the wire that goes to your high coil. you can just use decompression to kill the bike. your horn will still work if you disconnect this wire so that will still be their.