Battery will not charge on your 1986 v65 magna?

First, make sure the battery is good. Check the water level, then check the voltage. Must have more than 12 volts on the meter. If not, charge and check again. This will ensure that the battery does hold a charge. If all is good, then, with the engine running, check the voltage at idle, should have around 13 + volts, and at 2000 rpm, should have around 14 volts. If not, 2 things, the voltage reg. or the stator will have to be replaced.