I am not sure about the bike, but I am an electrian "residential" and I do almost all of the work on my farm tractors. A 12 volt system should generally have 12.7 volts on a fully charged battery. If it is less than about 12.5, then there is a problem somewhere. When a voltage regulator works like it should on other equipment, like one of my tractors, at a higher idle or midrange rpm the votlage should increase to around 14.4 to 14.7 volts. If it reads more than that, you are overcharging the system and burning your battery up. The battery will get too hot and boil the juice out of it. If your voltage doesn't increase at all when the bike it running, I would check the obvious first. Check all conections and check wires for possible breaks. Then go from there to the more complex issues. Good luck.
Jay