to the forum Reg
Bypassing the sidestand switch is a piece of cake
Disconnect the 2 wires from the switch & just twist 'em together completing the circuit
Then remove the switch & just tuck the wires away on the frame somewhere out of the way....
To make this a little cleaner, you could trace the wires back to a connector, probably somewhere near the backbone of the frame & cut 'em there before you join 'em to complete that circuit.
Another possibility of a culprit to your symptoms, could be a starter relay that's located near the battery...probably what's making that "click" when you hit the starter button.
It's certainly not going to hurt anything by doing the switch bypass 1st.....as a process of elimination.
Best of Luck & don't give up...you'll find it
Pretty common prob with alot of older Yamaha's