Assuming both rotors have the correct resistance
That's the thing though, they can't have the same resistance. Current is voltage divided by resistance. Ohms law. So 12.5v across 5.2Ω will draw 2.4 amps.
A 1.1 amp current draw means there's about 11Ω of resistance between the brown/green, the rotor and the ground.


1675994861787.png
 
That's the thing though, they can't have the same resistance. Current is voltage divided by resistance. Ohms law. So 12.5v across 5.2Ω will draw 2.4 amps.
A 1.1 amp current draw means there's about 11Ω of resistance between the brown/green, the rotor and the ground.


View attachment 235381

I am thinking right or wrong a short inside the regulator
So even the same rotor can draw different current .depending on how the top contact in the regulator connects.
And if other problems inside the regulator

There is a bypass resistor so if the contact dont land / connect as it should . Which happens with points also. that can affect
As the picture in post #41
Full connect a short brown to green
Not connected at the top it goes through the resistor but not open circuit if the resistor is not broken.

Andy can verify with his meter what the slip rings measure .Even if his meter has a low battery
it should give info .
By the way I do know i keep on like a demented parrot about the regulator. Cant we for now call it Experience.
I can change my mind if i need to .But I have had problems with these 3 or 4 of them One winter .Before I gave up
To much work with no success


1675996119758.png
 
As we say here in Australia - Are we having fun yet?

Just tested the “ new” ly installed rotor. 38 ohms between the rings and 0 for each to motor.
From all previous learnings that’s bad and This one is dead.
Think I’ll put the original back in and start again From the beginning.
On a side note ( Jan) I have soldered the new brush onto the old bracket to create a new correct right side brush. 😃
See al so photo of this and the Haynes manual specs. My brushes are 14 mm long. Original spec is 14.5mm. Tolerance is to 7 mm. So I’m just off new.
Just to be anal retentive can anyone confirm my brush holder is the right way up. Worked for 20 years this way up but I want to eliminate everything.
See photo and photo of battery voltage followed by voltage at battery when I’ve just hooked up fancy charger. I could take battery to a shop to load test. It’s managed to get me 2 hours riding twice with no charging. Let me know if I’m doing anything really dumb with my meter etc. starting to get really paranoid I have some sort of common procedural error.

Last of all, happy to take the bike onto the street and phone/ zoom or FaceTime anyone if that’s appropriate.
 

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I am thinking right or wrong a short inside the regulator
So even the same rotor can draw different current .depending on how the top contact in the regulator connects.
And if other problems inside the regulator

There is a bypass resistor so if the contact dont land / connect as it should . Which happens with points also. that can affect
As the picture in post #41
Full connect a short brown to green
Not connected at the top it goes through the resistor but not open circuit if the resistor is not broken.

Andy can verify with his meter what the slip rings measure .Even if his meter has a low battery
it should give info .
By the way I do know i keep on like a demented parrot about the regulator. Cant we for now call it Experience.
I can change my mind if i need to .But I have had problems with these 3 or 4 of them One winter .Before I gave up
To much work with no success


View attachment 235385
So far the only things not swapped out for known correctly functioning items are stator, rotor and regulator. First stator and first regulator swap outs seem to be with dud ones. We’ve done lots of testing with the regulator unplugged and are still seeing issues without it in the circuit. Could be a second issue but still haven’t nailed the primary.
 
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I don’t know what to say………
Just installed the corrected soldered brushes. Checked in manual and brush holder is the right way up.
Now the rotor that was testing high resistance has 5.3 ohms at the brushes when I compare inside and outside rings using the brushes and brush holders. It was the same rotor testing high before with no brush holder and direct visual contact to the rings.
Tested, retested and retested again to make sure.
How can it be? Does that mean I’m testing the rest of the circuit and not the slip rings now???

Seriously doubting my sanity. Clearly too many years at University and not enough in the field.

Green brush screw to tank bolt is 12.12 V with key on. Battery is 12.5V
Resistance on green brush ( key off) to tank bolt is 4.3ohms
Black brush to tank bolt ( key off) 1.4 Ohms.

Ive started posting more photos a details to make sure I’m not fundamentally messing something up.

I think I need a drink. Luckily it’s only 500m (546 yards) up the road to the local microbrewery. 🤷🏻‍♂️
 

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Not exactly sure but to measure slip ring resistance
I believe the brushes must be out It depends on the circuit.
Otherwise the rest of the circuit can affect the measured value.

fex think of it like this
2 resistors with the leads on each side soldered together if you measure across the one resistor .. the meter dont show the value the one measured across have.. It is giving the value of 2 resistors in parallel.
Sometimes it can be done provided one knows the circuit -- and in the resistor case know what the 2 resistors in parallel should measure.
In a real circuit "IN Circuit " Measurement it can be difficult.

How is the slap test now ?

If not OK
May I suggest 3 Resistance measurements across the slip rings on the 3 rotors One in the bike and 2 on the workbench
And report the values here
The one installed remove the holder with brushes or brushes so the measurement is across the slip rings

WE take it from there
 
Not exactly sure but to measure slip ring resistance
I believe the brushes must be out It depends on the circuit.
Otherwise the rest of the circuit can affect the measured value.

fex think of it like this
2 resistors with the leads on each side soldered together if you measure across the one resistor .. the meter dont show the value the one measured across have.. It is giving the value of 2 resistors in parallel.
Sometimes it can be done provided one knows the circuit -- and in the resistor case know what the 2 resistors in parallel should measure.
In a real circuit "IN Circuit " Measurement it can be difficult.

How is the slap test now ?

If not OK
May I suggest 3 Resistance measurements across the slip rings on the 3 rotors One in the bike and 2 on the workbench
And report the values here
The one installed remove the holder with brushes or brushes so the measurement is across the slip rings

WE take it from there
Yeah that was my concern measuring at the brushes instead of directly from the rings. Will complete this task first thing tomorrow and advise.
Slap still bad but will retest again with “correct“ brush brackets now.
 
Starting a spread sheet this am with testing flow as I do it. Could be handy for anyone to use. Will add in all the tests I can find in sequence. Happy to take input. Will upload when finished.
see photo for screen capture of first 5 mins of typing.
 

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Might be good news. Will fill you in on all the details shortly.
My rotor out and 2nd had one in. No Dice. Tested badly.
Testing mine out showed very low resistances. ( Kaput)
Took all 3 out and lined them up. Tested again. Only one tested good. It was the worst looking one.
So 3rd rotor into bike and hey presto.
That’s after charging all night and taking battery to Battery world for full test again this am.
Will upload spread sheet, results and do further testing to confirm but it’s looking pretty positive fir a change. Off to the airport for a pick up now. Spreadsheet might be a good addition to the linked check list so that you can view everything in a chronological complete order.
Stay tuned.
 
Dang.
I was hoping to provide an upload of the spreadsheet for future sufferers to use to collate their numbers and maybe add to it and build on it from ver1.
Apparently a spreadsheet file is not accepted.
Anyone any thoughts?

Good news. We have charge. 14.0V @3000rpm.
Just need to find a rewinder here in Australia.

So, key lessons learnt
1) Don't expect the guys at the classic bike shop to have done or do anything productive- you're better off on this forum. unless my rectifier was bad as well and the rotor their feedback resulted in an unnecessary replacement.
2) There is an exceptional bunch of experts here that are happy to share their time and effort to help out a novice. You might be good at mechanicals but not so much for electrics or carbys.
3) If you are borrowing or acquiring parts to swap in and out for testing you cannot assume they will work. ( I found a regulator and a rotor that did not work before I started testing with them). This will complicate your journey unnecessarily. Even if someone says they tested it and it was good they may not be correct.
4) If you get totally stuck- Stop, start at the beginning and write all the results down step by step. (Hopefully in a spreadsheet if I can work out how to get it out there).

Thank you all so much for your time effort and the overheating of your brains caused by me.
 
Good work you got it charging. With regard to posting the spreadsheet, I have had this problem. If I recall correctly the fix was to save the spreadsheet file as a PDF then post it here.
 
You could consider having a Voltmeter installed on the bike at least temporarily until everything is sorted out.
That is how I noticed the regulator overcharging .. Upsetting the Boyer Bransden Ignition dropping one cylinder when hot.
And hot is something different in Australia than here .Overcharging an old rotor is good to avoid.
 
Yes, I consider a voltmeter almost essential on these old girls. I never had one on any of my bikes in the past but I do have one now on both my 650s. One of the reasons is the availability of small, cheap digital units now. You can get them for around $5 .....

SmallVoltmeter2.jpg

SmallVoltmeter3.jpg


SmallVoltmeter.jpg
 
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