Well you can double check the starter relay, If you jump from the White wire Pin 5 to the Black/White wire Pin 3 that runs to the starter does the engine crank? If yes, apply 12 volts to Black wire Pin 1 on the start relay and see if the engine turns over when you step on the clutch.
If both of those work the wire to the switch or the start contacts in the ignition switch have failed.
I added a wiring diagram below.
Friday, December 16th, 2016 AT 7:56 PM