Thank you all for your replies. I thought about not running a safety relay at all. But I want to install a hidden starter button like the one on the photo below. My main concern is when this switch is defective there could be a permanent working starter motor. This happened once on an old Moto Guzzi I was riding, but then again Guzzi switches are notorious bad quality.
I thought about using a car light relay, but as I understand now this would not work because of the AC. I see there's some debate about whether it's AC or DC from the yellow wire. But this can be easy tested right? With a AC voltage meter and the engine running? Anyone done this?
I studied the wiring diagrams in my manual and it seems that the wiring of the safety relay changed over the years. On models 306, 366 and 476 the safety relay switches the positive wire to the starter button and from there it goes to the starter relay. On model 447 the safety relay switches the negative side with a wire coming from the starter button (which is now a ground switch) to the negative side of the starter relay. On models 533, 536 and 584 the safety relay changed back to switching the positive wire, but without a starter button in the circuit. The starter button remains a ground switch directly to the starter relay.
I don't think it makes much of a difference, but maybe with the starter button I plan to install it's best to mimick the 306/366/476 wiring. Any recommondations on that one?
View attachment 232975