I have a 1978 KZ400B1 I rebuilt recently and had out for one ride. The second ride I turned the ignition switch, pushed the start button and lost all electrical power. I checked the battery connections are clean and when checking conductivity found that if I unplug the right handlebar switch, which houses the on/off kill switch and starter button the neutral and oil pressure light will illuminate. I have purchased a new right side switch and if I plug in it will cut the connection and the lights will go out. I also installed a new ignition coil and have checked conductivity of the ignition switch, also good. Fuses have also all been checked with volt meter.
I have opened the wiring harness and found no bad or open connections. I am just about out of ideas and looking for potential solutions if anyone can suggest. Thank you!
I have put together a test plan (attached) that may help. It's looks heavy but should only take about 20 minutes. Info for colours etc taken from a diagram for a 77 ( there isn't a manual for a 78 on here)