Motorcycle Repair: CB100 charging problem, regulator rectifier, honda cb100

Question
Hi Chris:  Thanks for getting back to me so fast.  It is a new battery and the battery voltage stays at a constant 6.5 Volts even when running with the headlight on but I know it shouyld read more.  The 3V I am measuring is coming out of the white wire to the alternator.  Any other idras?
B.C.-------------------------
Followup To
Question -
Hi Chris:
 I have a 1972 Honda CB100 that has very low mileage that I just restored.  Everything works perfectly but the battery doesn't charge.  The alternator and the rectafier check out all right acording to the repair manual.  I only register battery voltage when it is running.  I have juice to all three wires going to the alternator when it is running.  The white wire will light a test light extra bright and flare up when you rev the engine but I only register about 3 volts from this whire.  That does not make sense unless maybe I am getting feedback from somewhere. HELP!
Answer -
Hi B.C.
 I hope that this is not the original battery, because, if it is, you have been wasting your time.  You need a new battery, if that is the case.

The real test of your charging system is to start the bike and check voltage across the battery terminals.

You should be getting 1-3 VDC over the rated voltage of the battery (i.e. 7-9 VDC for 6V system, 13-15VDC for 12V system).

If you are not getting the proper voltage, then there is either a short in the charging system or the stator has gone bad.

If the wiring is all good and the stator and regulator/rectifier are good, then the problem is the battery.

It's all a process of elimination.  You have the manual, so all of the specs and wiring diagrams are there.  Everything works in a logical order, so just remember the words of Sherlock Holmes; "examine all of the evidence and eliminate everything that doesn't fit.  Whatever is left, no matter how improbable, is the answer."  It works for fixing things as well.

Good luck.
FALCON

Answer
Hi B.C.
 The problem is that you either have a bad stator coil or a short in the charging system.

What tells me this is the fact that you are getting only 1/2 VDC over the rated voltage of the battery.  You should be getting between 8-9 VDC for the stator to actually be good.  So, as I said, you either have a short in the charging system or you have a stator coil that is about to completely fail.