Go look at a wiring diagram before progressing to far as far as the color codes... The yellow/red is USUALLY the coil power. I know they pull coil power from this area on some of the KZ550s. The BLACK is usually the trigger for the solenoid and that is the wire coming from the start button. The solenoid sometimes has a ground wire and sometimes doesn't, depending on the model. The ground is supplied by the bolts in the starter where they meet the engine cases. If there is a ground wire, it should likely be connected to the reg/rec and may be BLACK... The ONLY power that should come out of a solenoid should be on the big lug where the starter wire connects but my memory tells me that a 550 may have power coming from this area for the coils. Perhaps loudvhx will chime in as I don't have diagrams for this bike only a poor, old and very faulty memory. I worked on a KZ550 race bike last year and I dimly remember power coming from the solenoid area and not the normal path out of the right switchgear to a connector above the coils.
