I am getting a bit confused now Beef. I feel I need to see the bike and trace the wiring as some things seem to be non standard. The Black wire on the Starter Solenoid should be positive (when the starter button is pressed) and the Yellow/Red wire should be negative (constant).
I have recently (last night) run through this part of the circuit with Tango and this has been confirmed and cured his problem. If yours is wired differently, which it shouldn’t be, then I am at a bit of a loss and would need to see it.
Do not get despondent with her we can fix it with clear pictures.
If yours has been wired up wrongly then maybe something has blown. All parts of the circuit need to be tested until the problem is identified.