Impulse txl 50 won't crank
 

I recently bought this for my nephew. It's a 1999 make. It won't crank over to start. No click. Nothing!! I just put a new, fully charged battery and a new wiring harness on it. Can someone please tell me what else could possibly be wrong with it. It would be greatly appreciated.

so the inline fuse is ok? how about the wiring harness/loom quick connects around the ignition key area? sometimes the blades inside the quick connects will back off and not make good male/female contact thus causing problems. with the key "ON", take your ohm meter/voltmeter and trace out the voltage and i'm sure you'll find the problem shortly. no pun intended.

you may even try to take a screwdriver and touch the solenoid posts together to see if she cranks. if she does, then continue tracing wire issue cause you ain't getting the voltage to the solenoid. if she don't then continue tracing wire and follow voltage until you don't find voltage and therein should be the problem. i would hate to say voltage regulator and you replace it when it was fine to begin with.