So those wire combinations jibe with the headlight relay connector, the key switch itself should have 3 wire connector: red, brown & blue (according to US '81 model now on that part only). No matter, as the result is the same; too much voltage drop. I don't know if 10 volts at the regulator (and rotor) is enough to get the alternator charging.....@ Jim, et al??

You could bypass the key switch with a temporary jumper at its connector - red to brown - just long enough to see if it cures the voltage drop and produces 12V on brown @ regulator. If it does that, I think you should then get full magnetism at the rotor.
 
So those wire combinations jibe with the headlight relay connector, the key switch itself should have 3 wire connector: red, brown & blue (according to US '81 model now on that part only). No matter, as the result is the same; too much voltage drop. I don't know if 10 volts at the regulator (and rotor) is enough to get the alternator charging.....@ Jim, et al??

You could bypass the key switch with a temporary jumper at its connector - red to brown - just long enough to see if it cures the voltage drop and produces 12V on brown @ regulator. If it does that, I think you should then get full magnetism at the rotor.
Ok will take a look. Could have easily followed the wrong cable bundle in the dark. Will try the jump and let you know.
The voltage drop suggest a leak and the pre-existing magnetism could be the result?
 
Think I have the right block now. Cable was all bunched up behind the bucket after install.
The further we go the more suspicious I get about the headlight switch.
Red=11.14V, Brown=10.91V, Blue/Red=1.3 mV, Blue= 1.3mV.
Certainly looks like one of the components plugged into the loom is sucking the system of juice.
Am I right in thinking that everything seems to be connected to everything else. Sort of feels like a blown indicator globe might create the butterfly effect.
 
gggGary posted this picture below
At the green at the Brushes there are is ca 10,

Voltage to ground on green=10.3V , black= 6.6mV

Battery
key on=12.13V
key off= slowly climbing from 12.6V


That means if it is connected according to the Schematic and fuse sits ok and no drop in the Main Switch
in the Ignition Lock and so on that you have 12.13 V on the Brown going in to the Regulator
But on the green coming out you have 10.3


Please measure Voltage what is going in to the regulator on the Brown
and what is out Green of the regulator
Both measured to ground

Apologize if this is mentioned above

The Circuit part is not large

Battery --Fuse ---Main Switch -- Regulator --Regulator Brush 1 Green -- ..rotor ..Brush 2 Black -- Ground

My money is / was on the regulator .If i Recall right it sits at the topmost position at start up shorting Brown to green not giving any reason for the 2 V drop If it is there at the regulator please measure r as above We reevaluate Brown green on regulator

Can try to clean the contacts on the regulator with some Grinding piper or a small file + solvent


1675773726226.png
 
Brown wire to/ from regulator key off= 100mV, key on=10.3V

Yes one green wire and one black to brushes.
Voltage to ground on green=10.3V , black= 6.6mV

Please measure Voltage what is going in to the regulator on the Brown
and what is out Green of the regulator
So the issue appears ahead of the regulator.

Red=11.14V, Brown=10.91V, Blue/Red=1.3 mV, Blue= 1.3mV.
We've got ~ a full volt drop ahead of the key switch (not normal), then a .2 volt drop at the switch (normal). The standard arrangement of that circuit is: battery positive to solenoid, solenoid (battery side) to main fuse, main fuse to switch. Then we lose another .6 volts to the regulator; that path is key switch to fuse box
Brown wire entering fuse box =2mV key off, 11V key on
then, fuse, brown wire out to regulator (10.3VDC) with a bunch of stuff in parallel also on brown wire.

Problem: no (weak) magnetism @ rotor with key ON, very weak magnetism noted with key OFF.

Possible AGM playing games under load (remote).
Possible excess resistance in wiring to regulator (connections, etc.)
Possible stray draw??.....

We can test stray & excess draw: remove battery negative cable and place a multimeter - scale to milliamps - between battery (-) post and the negative cable, take readings; with key off, key on, key on removing each 10A fuse one at a time.....

@Jim this is your call for assistance:)
 
Thinking out loud here

If I get this right it is the same Voltage before and after regulator

Voltage to ground on green=10.3V
Brown wire to/ from regulator key on=10.3V

If I remember right it is supposed to be the same but higher
If there is a partial short in the rotor or the Regulator wont it pull down the System closer to ground
Namely mentioned 10.3

?? Unplug the regulator .. not connected switch Power on and measure Voltage on Brown from bike -- upside brown to ground -- that before would enter the now disconnedted regulator
see if it still is 10.3 or higher ??
 
One other thing that hasn't been discussed and - maybe - hasn't been verified is the brushes: length, contact with slip rings, continuity to connector. Just tossing that in in case the low voltage to regulator ain't the problem
 
Skimmed over this thread so apologies for not being completely read in...
Re: Suspected residual magnetism or partial power to the rotor... verify you still have the slight residual magnetism and then disconnect the battery and see if it's still there? That'll tell us if it's residual or battery current getting to the rotor.

The voltage drop at the key switch needs fixing, but that gives the regulator a false (low) indication of battery state. That usually results in overcharging... which isn't the problem here.
 
One other thing that hasn't been discussed and - maybe - hasn't been verified is the brushes: length, contact with slip rings, continuity to connector. Just tossing that in in case the low voltage to regulator ain't the problem
Brushes checked And exceed requirements listed in Haynes manual. I think they need 10 mm mine were 15-17 mm. Can’t remember as it was the first thing checked off the list some weeks back. Pulled brushes last night to use contact cleaner on inner slip ring just to be sure. Below is shot of setup as per last night.
very unlikely to be connectors to regulator. Cleaned, brushed and shiny when I installed loom.
 

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Cleaned spades of regulator with 2 brands contact cleaner after removing them from plastic plugs and brushed with steel brush. “Shine like the top of the Chrysler building”.

Even with the battery unplugged we still have residual magnetism at the steel nut on the rotor! Not what I was expecting. 😱
Livin and learnin. So it looks like this is not a current draw.

Tested voltage at brown wire of regulator with regulator unplugged. 11.92V. Dah daaaaaa. ( 12.5 at battery)
Then plugged in regulator and Tested again on regulator side of plug to only get 10.3 in the circuit now.

Dead regulator? Was leant one by a mate to substitute in and I think it was dead. ( Green windings beside it got really hot after only a few seconds in place, was quick to remove it. )

Made up a second jumper wire with spade and female spade each end. This adds to the other I recently made with alligator clips each end. So I can do the jump mentioned earlier. Just have to go back thru the thread to find it.
 
Even with the battery unplugged we still have residual magnetism at the steel nut on the rotor! Not what I was expecting. 😱
Livin and learnin. So it looks like this is not a current draw.
That's good. Process of elimination... one less rabbit hole to chase down.

With the regulator disconnected, jumper the brown wire (batt voltage) to the green wire going to the rotor brush. That's gonna bypass the regulator and energize the rotor with full battery voltage. What does the battery voltage read at about 3000rpm now?
 
That's good. Process of elimination... one less rabbit hole to chase down.

With the regulator disconnected, jumper the brown wire (batt voltage) to the green wire going to the rotor brush. That's gonna bypass the regulator and energize the rotor with full battery voltage. What does the battery voltage read at about 3000rpm now?
Any risk to master fuse, meltdown of plugs etc? Rather nervous on that one but happy to proceed ……?
 
Well, here's always a risk when it's not working right, so be ready to kill power if you need to.
But all we're doing is sending power to the rotor that it would normally get from the regulator. Nothing should get hot or blow fuses.
 
"Took the leap of faith and did the jump. Result 12.6 voltage at battery at 3000rpm."

Shoulda had you do the slap test at the same time.... sorry. Wanna to do it again?
 
It's gettin' late here, so I'll check back in the morning.
Jumping power straight to the rotor tells us that it's still not charging when bypassing the regulator. That tends to indicate the regulator isn't the problem.
The slap test is a bit subjective, but a good slap means the rotor is good which leaves it down to the rectifier or the stator... or wiring of course.
A weak slap most likely means the rotor or brushes

EDIT: For the slap test, you just need the brown/green jumper. You don't need to run the engine.
 
It's gettin' late here, so I'll check back in the morning.
Jumping power straight to the rotor tells us that it's still not charging when bypassing the regulator. That tends to indicate the regulator isn't the problem.
The slap test is a bit subjective, but a good slap means the rotor is good which leaves it down to the rectifier or the stator... or wiring of course.
A weak slap most likely means the rotor or brushes

EDIT: For the slap test, you just need the brown/green jumper. You don't need to run the engine.
Added in slap test.
Result: Improved magnetic suck with cover off but still pretty weak when I hold the cover in place and repeat.
I’m pretty sure it was better months back when I first had some issues with fuses heating up and tested it.
Just looked at the video again- mine might be the same. I think I might have been getting mislead by the noise of the key clicking on and off During the video. More of a phifffffff test than a slap test.
 
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Your inner brush looks strange. It looks like an outer brush was installed over the framework of an original inner brush. Here's a pic of the outer and inner brushes. Note the larger bracket on the inner brush, held in place by 3 screws .....

EarlyBrushes.jpg


I don't know, maybe what you've got will work fine, but maybe not. Maybe the brush isn't getting grounded as well as it should (it grounds through the 3 screws). Maybe that's why your slap test is weak. You might want to get yourself an actual inner brush.

EarlyBrushMountLabeled.jpg
 
Your inner brush looks strange. It looks like an outer brush was installed over the framework of an original inner brush. Here's a pic of the outer and inner brushes. Note the larger bracket on the inner brush, held in place by 3 screws .....

View attachment 235248

I don't know, maybe what you've got will work fine, but maybe not. Maybe the brush isn't getting grounded as well as it should (it grounds through the 3 screws). Maybe that's why your slap test is weak. You might want to get yourself an actual inner brush.

View attachment 235249
I see. You’re right. Pretty sure I have both older shorter ones and maybe new ones. Been a bit paranoid about brushes. I reckon it’s grounded but true, maybe not as good as it needs. Will dig into this one and let you know. Cheers.

Just checked Geoff’s Xs here in Australia and May have found the source of confusion. He lists 70-79 and the two different ones and 80-84 as the identical ones. However he notes in bracket for TCI ignition. Really he should just say TCI ignition or points ignition to differentiate. Had a feeling I may have only been getting oomph out of one ring.
Will sort it. Could this be the source of the voltage drop though? I suspect not?
 
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