tank wont start
 

My tank 150 just clicks once each time I try to start it. If I do it about 100 or more times, it eventually turns over a bit and starts. I thought it may be the starter, so I put a new one on. Same thing. Click, click click. It does also make a clicking sound when I ride it, and the headlights flicker. Can anyone tell me where to look in the wiring to possibly see a problem, or is it another issue?

Find the starter solenoid and make sure the connections are tight there, after checking the battery connections first. If they are then you're next test is to take a screwdriver and jump the terminals of the solenoid. If it spins, the solenoid is bad, or a bad brake switch, or a bad starter button. Time for some detective work with a volt/ohmmeter.

If it doesn't spin then you either have a bad ground or a bad battery.

Everything seems to be getting current when it should, but it doesn't seem like the solenoid is getting enough. Could it be the regulator? I tested it with a multimeter and could not find any continuity.

Did you test for continuity with the brake handle pulled? There's a ground wire and a power wire to the solenoid so jumping it should spin the starter. That's the first test to determine if the problem is in the solenoid, starter or starter circuit.