Here is the # for a 82 750-4 cyl LTD Chain driven.
26001-1298
Discontinued and on Kawasaki.com I do not see a cross reference for this harness.
But under a Google search I found this:
www.speedsupplies.com/cartdisplay.asp
Which may be that you can still get a new harness from a warehouse?
Try calling Jeff at Z1 and ask if he can supply the new main harness for you, 315-926-5054.
Or repair what you have now, harness back to stock parts, or keep the Dyna and fix the Charging issue. I think you have a charging issue either way. Best to test the Current use by the system, and the Current made by the Charging system, all measured in AMPs. That way you know your electrical system is correct. You should have the 3 phase 20 amp alternator, your charging voltage should be above 14v at the battery, and less than 15v.
You can fix it between your Dad and some help Here from KZR, do you have the Service manual?
