I have a K321S engine on a power king tractor. The PO butchered the wiring and I'm trying to put it back to the original setup. I bought the power king ignition switch and tried hooking it up by the wiring diagram in the manual but there isn't a complete diagram on the ignition wiring, i.e. where does the single wire from under the front cover go. There are 2 wires in a cover that goes to the rectifier and a third wire that I have no idea where it goes.

Hi,
My guess is that it goes to the condenser. Just a guess; try picking up an engine service manual here:
K&T Parts House Lawn Mower Parts and Chain Saw & Trimmer Parts
Peace,
Clarke