TOPIC:

That is a very common problem. Dirty fuse holders is often the cause. Next likely would be bad contacts at the ignition switch. Next would be bad connections at the various connectors in the circuit.

I'll go over them in that order, really appreciate the help.
THANKS

Checked the fuse holders, checked the ignition switch (these are easy to hot wire ), checked the bullet connectors in the headlight & back side panel.
Still no go.
Thought I was on to something because when the headlight is removed the voltage at the regulator gets closer to the battery voltage.
But when the headlight is on the gap between the two is back.
I'm trying to understand the relationship between the headlight and the brown wire but get lost w/ the "reserve lighting box".
Is it just that they both get power from the main white wire?
Some other relevant notes.
Brown wire jumped to positive at the ignition bullet connector still read low at the regulator.
I had a 2a charger hooked to the battery to hold voltage while testing.
The 20a white wire fuse got hot when after the key was on for a prolonged period.
Anything else to try short of pulling the whole harness apart?

The bike has fully stock wiring, correct? No Dyna S ignition? No extra lights?

There is a bad connection somewhere between the battery and the brown wire on the reg/rec. The more current you use, the more that bad connection drops voltage. If you turn the lights off, the connection doesn't drop as much voltage.

Keep the meter's black wire on the battery's positive post. Then take voltage readings with the red meter lead at the following points:
The red/white wire on the 20 amp fuse.
The white wire on the 20 amp fuse.
Both white wires at the ignition switch connector.
The brown wire at the ignition switch (the diagram shows this to be a single wire, not in a multi-connector).
The brown wire at the reg/rec.

This should be done with the lights on.

Yes, bike appears completly stock.
Not sure what a danaS is, but coils appear original.
No extra lights
Will I get a reading pos. to pos w/ a digital meter?
I'll give it a shot when I get home.
THANKS

enormiss wrote:

Yes, bike appears completly stock.
Not sure what a danaS is, but coils appear original.
No extra lights
Will I get a reading pos. to pos w/ a digital meter?
I'll give it a shot when I get home.
THANKS

Yes, but the readings will be small. You will be measuring the actual voltage drops (.1 to 1v range, most likely).

You can then do the same tests with the meter's black lead on the battery's negative terminal, if you want to see than actual voltage levels rather than the voltage drops.

After all that, the next step is to do a similar thing to the ground side to make sure that is not the problem.

That method was a whole lot faster then taking the batt then wire voltage and subtracting the difference
Learned something new, THANKS!
Here's what I got...
Batt to Red/Wh @ fuse = .13
Batt to White @ fuse = .33
Batt to White @ headlight connector = .72 & .89 (it splits into 2)
Batt to Brown @ headlight = 1.03
Batt to Brown @ Reg/Rec = 1.11
So it looks like I need a new fuse and to take the tank off for a closer look at the white wire?

Yeah, unfortunately you have what is probably common on old bikes. As you can see you are losing little bits of voltage along the path, which add up to the total drop at the brown on the reg/rec.Your losses are just a little too much, and should be cleaned up. It is normal for a fuse to have a small drop, but make sure it is not from dirty holders.

Taking the ignition switch apart is tricky, but not impossible. I don't know what your finances are like, but you should be able to get a new ignition switch if you want, but then you'll need to carry more keys.

Also, some recommend using dielectric grease on connectors, but I have seen the grease cause this sort of problem so I stay away from it. I hate trying to clean that grease out of connectors.

I'll give the white wire a close look, and if I still come up empty I'll add another fuse and lead to the ignition.
Instead of one fuse and wire splitting into two, I'll have two fuses/wires from the batt to ignition.
I did take the ignition switch apart and it was in very good shape inside.
Cleaned the contacts and reassembled.
Same w/ fuse holder.
Maybe I'll find something loose under the tank.
Thanks for all the info!

loudhvx wrote:

It is normal for a fuse to have a small drop, but make sure it is not from dirty holders.

Fuses also just go bad with age. They gradually get more resistive. If they are older than two years, chuck them in the trash.

Replaced the fuse on the main white wire, as well as added a 2nd fuse and wire instead a single branching off into two near the ignition.
I still have slightly more than 1 volt loss at the reg/rec.
This is driving me nuts... All the wiring appears to be original and in very good shape.
So heres some more info hopefully leading to some more suggestions.
The two white wires going into the ignition
One controls everything on the bike but the turn signals.
The other just the turn signals
The main wire is drawing 6.3 to 6.5 amps depending on the battery voltage.
That is non running, headlight on low beam, battery on a 2A charger.
Not sure if that is "normal" or not... I'm hoping it is high since my fuse still gets warm.
If I put the high beam on the fuse gets HOT.

Those amps are normal. If your fuse gets hot, you have bad and/or corroded fuse clips. The fuse runs pretty warm. How warm is considered "hot" is hard to say.

The fuse is new & clips are clean & tight.
There's very little loss from one side clip to the other on the meter.
I'll go with the fuse normally runs warm.
The amp load with the the headlight on high was 6.7A
I think I'm just going to add in a relay so the regulator gets true battery voltage and call the bike complete
When winter rolls around maybe rewire the whole bike.