Does the GEN lamp come on when you turn the key to the ON position, before starting the engine ?
To test the alternator output, you need to fully charge the battery, start the engine and bring the rpm's up to about the 4000 area, the alternator should be putting out it's maximum in this general area .
Usual range is 13.9-14.2 volts, or there abouts, all bikes are a bit different .
About the only common thing that I can think of, causing a drain on the battery, would be a bad diode on the diode board just above the alternator .
But usually the GEN light will glow dimly it a diode has failed and allows electrical flow in both directions, instead of acting like a check valve and allowing electricasl flow in one direction .
A good cleaning and checking of the connections is a good idea .
There's one connection that gets overlooked due to it's location, it's the connection fro the alternator output, to the starter, it's a bit odd, the positive cable from the battery goes to the post on the starter, the wire from the alternator, goes on the same post .
This is hidden by the top cover of the engine .
