First thing you need is a volt meter digital type is the easiest to use!
Charge the battery, it should read 12.6 dc volts when fully charged. DO you have modified headlights? They could draw too much current, draining the battery. Run the bike at 5K rpm's if the bike is charging you should have around 14 volts dc across the battery terminals. If the run voltage test fails and you only get 12 volts. Check all of the connections between the stator and the regulator, then retest. Still fails, disconnect the stator wires. Run the bike at 5K rpm, measure the ---AC--- voltage between any two of the wires ( 3 tests) should read 75+ VAC The reading should be the same between all three tests If one pair is very low- the stator is bad, also check from the wires to ground, with the bike off- you should not get a reading. If you get to this point and everything checks Ok chances are the regulator is bad