1980 kz750e starting issues

I have a 1980 kz750e and I just rebuilt it but the guy that had it before me did some weird stuff ( dumbass stuff) well anyway when I put the key it and set it to run the voltage gauge doesn't show any power and the lights on the instrument cluster is dim as soon as I hit the start button the voltage spikes to 13 and the lights get bright but I can't get the starter to turn over any idea's and does anyone have a wiring schematic for this bike I have the manual but it's only trouble shooting not actually wiring diagram


Thanks

1980 kz750e
1980 kz650h
1982 honda cm250 custom
1938 bmw r34
2000 kawasaki ninja 250

Look at this website for a wiring diagram: www.mbsween.com/kz750l3/manual.html
If no luck, take your cursor and go to the top right corner of the home page of this website and look for "Filebase", it lists a lot of wiring diagrams for bikes.