Motorcycle Repair: Charging system, regulator rectifier, check voltage

Question
I have a 98 STC i just put in a new battery about 3 months ago and it almost dead already.
I push started it and got it running but i noticed the head light is very dim so that tells me that the battery is not getting charged while the bike is running.
Can you help me with this
Thank you

Answer
Charge the battery first then use a DC volt meter and check voltage at battery. Now start bike and as you raise the rpms up the voltage to the battery will rise. If it does not rise or is lower when bike is running the you have either a regulator/rectifier or stator bad. Johnny