Stella - 1977D survivor, back on the road.

Indeed!

BTW - that photo of Daniel is a really good likeness of him (we met in Phoenix in March). DB is from NYC but I think he is much more comfortable living in the Wild West in his buckskins and coonskin cap. :D
 
The trip was superb Daniel - except for the danged rain. Nice roads, pretty towns, great food and fun riding though.

P
 
Oh yeah - NYC Yankees and Canadians don't take no for an answer where the weather is concerned.
 
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There's no such thing as bad weather............................just inappropriate clothing :)

A few years back, I made a 5 day motorcycle trip through BC. I got rained on 3 out of the 5 days. My rain gear kept me completely dry, so the trip was very enjoyable.
 
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....or as my OPP riding instructor used to say...."If you don't have a sense of humour about the weather, you should not be either a Canadian or a motorcyclist."

Wise man...hilarious sense of humour for anyone but particularly for a grizzled old LEO.
 
TwoManyXS1Bs said:
For the 70-71 XS1/XS1Bs, I'm sure that the black grounding wire from the regulator goes only to the grounded inner brush, and is the only source of grounding for the regulator.
Click to expand...

This is mighty interesting!

2M, I think you might have inadvertently solved my ongoing charging issue. I missed this detail in my rewire and in its current configuration Stella's regulator is grounded to the neg lug independently as is the black wire from the inner brush. Could this cause charging voltage to drop as the battery reaches full?! Something about changing resistances and voltage drops as the battery reaches full charge? Measuring battery voltage against itself would surely give different results than measuring it against the brush's ground potential through the stator and case. Hmm...

Stella's battery always has enough juice to turn the starter. But I've not been thrilled with the fact that cruising charging voltage drops to the low 13s as I ride and the battery reaches full charge. I know 5twins reports a dip on his after the battery has a chance to charge, but I've felt 13.3-13.5 is a bit excessive. When I've let her sit for a week or I've been using the starter on a lot of short rides the charge is up at 14.1-14.2, so I know she's capable of it when needed.
 
I don't think anyone has verified yet that the later models are wired like the XS1. Only the XS1 wiring diagrams show the black brush wire being independent, running just from the brush to the regulator. All the later diagrams show the black brush wire connecting to the common black ground wire in the harness, which connects to the regulator with one of it's branches. I suppose you could try interconnecting those 2 grounds.

Now that I have a full time voltmeter, I can report some numbers. Yes, my charging voltage does dip after the battery gets replenished, but not as much as yours. I'll see a high of 14.1 or 2 right after starting, headlight on. That will drop to about 13.8 after the battery is replenished.
 
Ditto, the votes are still out on that regulator black wire.

Daniel, there's a couple of tests I'd like you to try. They measure the voltage drops, directly, between the battery and regulator.

If you study the torturous wiring paths from the battery to various things, there's wire segments, crimp connections, connector plugs, fuses, all in the paths, and each contributes to the overall resistance in each path. The regulator's brown power connection is near the end of the brown wire's path, and is subject to voltage drops from all the devices between it and the battery.

What you're going to test is voltage drops between the battery and the regulator connectors. Super-easy on the 70-71s, since the regulator connector is right next to the battery, as seen in Angus's pic:

Angus67-71XS1B01.jpg


With the engine running,

1- Connect voltmeter (+) lead to battery (+),
Connect voltmeter (-) lead to regulator brown, on the reg side of the connector.

Observe voltages at idle and above,
Cycle various things on/off during this (headlight, signals, stop, horn).
In an ideal world, the voltage drops would be less than 0.2 volts.
An acceptable drop would be less than 0.5 volts.
Any drops above 2 volts warrant immediate attention.

2. Connect voltmeter (-) lead to battery (-),
Connect voltmeter (+) lead to regulator black, on the reg side of the connector.
Observe voltages at idle and above, same as above.
 
DanielBlack..........................you're chasing ghosts. All grounds on your bike should be at the same potential, i.e. at the same voltage potential as the battery negative terminal. Disconnect the battery positive and negative cables, to take the battery out of the investigation.
Use your VOM to measure the resistance from the large negative cable to the regulator ground black wire and also measure to the grounded brush on the alternator. Those 3 points must all have 0 ohms resistance between them. This applies to any model from 1970 to 1979. If you find any resistance that is greater than 0 ohms, then you really do have a problem, which would need to be corrected.

It is not normal for the charging voltage to decrease as you drive down the road. If you see a high of 14.2 volts, then it should remain at 14.2 volts as you drive along the highway.

When I start my bike,and turn on the head light, the voltage will be at about 13.5 to 13.7 volts with rpm idling at about 1100 or 1150. Within a few minutes I adjust the idle to 1200 rpm and the voltage is about 14.1 or 14.2 volts. As I travel out on the highway, for hours at a time, my voltmeter always stays at 14.2 volts. Of course when I'm stopped at an intersection for a red light, with turn signals flashing, the voltage drops down to 12 to 12.5 volts which is quite normal.

Your alternator has the ability to produce 200 watts at 4000 rpm, but your bike likely is only consuming 160 or 170 watts, so that means the regulator takes the voltage up to its set point (lets say 14.1 volts as an example) , and then reduces the rotor current to prevent the voltage from going any higher.
 
I have my old 77D harness still and will confirm whether or not the regulator's ground is separate from the rest of the black wire system.

I should get to those tests today, thank you.

One thing to note is that in my rewire the regulator's sensing wire is close to the battery a la PamcoPete's, not at the end of a long chain:

Battery
fuse
relay
tri-bullet connector(splits to send to lights, ignition, etc.)
regulator connector
regulator

Harness check and test results to follow after this morning's job interview.
 
On my 77D harness the regulator connector's ground has continuity with all other black wire points.

Preliminary results, pending more thorough investigation. I couldn't quite get into the regulator side of the connector without removing it from underneath the battery box.

Neg batt lug to reg black 0.0ohms
Neg batt lug to inner brush 1.0ohm

Pos batt lug to harness side of reg connector ~200mv @ idle with all my LEDs on, no headlight. Approaching 0mv when revved.

More investigation as soon as I have the chance to pull the bracket and get into the reg side of the connector.

IMG_20170324_115717399.jpg
 
Oh, man. I had to grind thru this whole thread to resync in my head whut's goin' on here. About halfway in, I fell asleep.

Sorry, Daniel, I had you chasing the wrong tail.

Anyway, to summary recap, Daniel initially experienced a rectifier failure due to some wierd backfeed thru the yellow wire. After that, it was rectifier failures, with a wierd commonality of failures in the negative side diodes. Followed by a better rectifier, but with continued undervoltage. The stator was also replaced, the original showing signs of overheating. This is in the postings between late March and early April.

There IS one scenario that would bias current/heat failures to the negative diodes. The yellow wire, or the common tie where the yellow wire connects.

Any and all current delivered thru the yellow wire would come thru the negative diodes, ONLY!

If there's sufficient current, or intermittant grounding, thru that yellow wire, the negative diodes would have to supply that, in addition to their normal load. There's the imbalance.

If grounded, there would be essentially a closed loop between a stator winding and its associated negative diode. For all 3 windings and diodes.

Note that this has NO effect on the positive diodes.

There wouldn't be enuff current from the stator windings, even if the yellow wire was shorted/grounded, to burn the wire. But, this extra current would overly heat the stator windings and the negative diodes. So, it wouldn't display the normal 'shorted', smoking, burning symptoms typical of a battery-fed current source.

This would also reduce the full-wave output of the rectifier to a partial full-wave (subdued 2nd half) output, reducing total output.

Am I over-rambling, again?
 
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Keep it coming!

I think I'm following you and see the current loop you're talking about but my understanding of the yellow's path may not be up to snuff.

If I understand correctly, the yellow wire originates at the stator windings' junction and runs through the starter safety relay's primary coil and then to ground. That path to ground (minus the SSR) seems to be indicated by this diagram on p144 of the factory manual. Are you thinking a short further upstream than the SSR?

IMG_20170907_145637939.jpg
 
I'm going to hazard a guess here and say that probably every one of these bikes exhibits a slightly different charging output. There's so many variables, so many connections and components. A not-quite-perfect connection, or several of them, would most likely draw down the max output. Mine seems to charge fine, or at least good enough, but I don't seem to see output numbers as high as some others report. But I never have my battery run down too low on me. I never have to trickle charge it between uses, even if the bike sits a week or so. It's always been this way, even when I had the original regulator that was only putting out mid 13's for max voltage.

My idle voltage is quite low, especially with the headlight on. It drops to the high 11's, back up to mid 12's if I switch the light off. I also noticed the headlight seems to suck more juice at idle than at speed running down the road. If I switch the light off while driving, the voltage output only rises a tenth or 2. At idle it rises like 3/4 of a volt.
 
DanielBlack said:
...If I understand correctly, the yellow wire originates at the stator windings' junction and runs through the starter safety relay's primary coil and then to ground.
Click to expand...

That sounds right.

DanielBlack said:
...That path to ground (minus the SSR) seems to be indicated by this diagram on p144 of the factory manual. Are you thinking a short further upstream than the SSR?
Click to expand...

I think that diagram's wrong. On the 70-71 bikes, there is NO center-tapped yellow wire.
ChargingColor2.jpg


72-on, that center tap goes to stuff. Grounding it, as shown in your diagram would be a no-no, and would represent what a grounded yellow would be like...
 

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