I’m wiring a kill switch, “on / off” for a Bosch Du4 magneto. This vehicle has no battery or coil. In order for it to not send a spark to the plugs when cranking over, how do I wire for an “off”?
Ground the magneto's points to turn it "off".
Run a wire from the junction inside the inspection cover where the points and condenser meet to a single throw switch. Then run a wire from the other side of the switch to a good ground.
"Off" (as in no spark) would be with the wire from the point cover plate on the magneto connected to ground. This would mean that your switch should be in the "on" position, providing continuity thru the switch.
So the 5th terminal, when grounded would produce no spark to plugs? The other 4 terminals go to the plugs.
Yes. There are the four high voltage wires that go to the spark plugs. The low voltage terminal on the front of the points cover is what will get shorted to ground through the Kill switch.
Here is the factory diagram from "old Mexico" late at night.