I think that they must be self earthing, as they have a metal body which is firmly clamped to the saddle on top of the magneto, which itself earths via its mounting bolts and the magneto platform. I’m no ‘Sparks’ myself as I am partly colour blind, which is a real problem when playing around with wiring harnesses ! My late father was even more paranoid about electrics… “You can’t see it, you can’t smell it, and when you feel it ,it kills you.”
Brian
