Second Bad Stator in a YEAR?

[RadWingDad]

Hello beautiful people,

I just finished replacing the stator in my '84 GL1200 Interstate a month or so ago. Last week I went out for a ride and the battery died mid-ride. AAA got me home and after some testing I thought it was the regulator/rectifier. I replaced that and that's when I noticed when I tested the stator I was getting less that 0.5V on all three wires. Aaaah, crap! Is it possible that riding with a bad RR would cause the stator to fail? Any suggestions are appreciated.

Some back story:
I bought the bike in April of 2021. In late May of 2021 the stator failed. I took my sweet time getting started, and while referring to articles on this site and others, and videos on YouTube, I replaced the stator myself. At some point around August I lost my momentum and it took me FOREVER to get the bike back together. I went on a few short rides without any issue during breaks in the cold. Last week I went on a longer ride, about an hour, and the bike started acting like it was starving for fuel. Way down on power, missing, etc. I managed to coax it into a driveway so at least I was off the road. At that point I realized it must be the charging system because I could see fuel in the tank and the starter wouldn't even turn. After getting the bike home I charged the battery overnight and the bike fired right up. I tested the RR according to the instructions in the service manual. No continuity anywhere. So I replaced that. Then I tested the new RR and still no continuity. Weird. So either I'm testing it wrong or the new one is bad, too. Or maybe the first one wasn't bad. So anyways, I decided to test the stator and got less than 0.5V on all wires. So I may be looking at another bad stator? The bike has about 69,000 miles on it (Nice!) and I could tell from the wiring from the stator to the RR that the stator had been replaced twice before I replaced it last year. So Old Wing (as I affectionately call her) has killed four stators.

[Rambozo]

Please describe how you tested the stator. And what AC voltage did you get?

[RadWingDad]

Stator test:
With the engine running at 3K RPM, and the multi-meter set to 20VAC, I tested each pair of the three yellow wires at the connector to the left of the battery: A-B, A-C, and B-C. I got between 2.27V and 2.31V on each combination.

Regulator/Rectifier test:
With the engine off and the multi-meter set to the diode setting, I tested each yellow wire with the red and green wires in the connector. I got no continuity anywhere. With the engine running and the multi-meter set to 20VDC and connected to the battery terminals, I saw no increase in voltage as RPM increased. With the engine idling and the multi-meter connected to the battery, I can watch the voltage in the battery decrease over time.

[Rambozo]

When testing did you have the three yellow wires disconnected?
Getting a low voltage is strange. Usually it's an all or nothing, or dead on one pair but good on others.
With the yellows disconnected, you can also check for shorts to ground with an ohmmeter.

[RadWingDad]

Not disconnected. I can repeat the test tomorrow with the wires disconnected.

[DenverWinger]

Rectifier test also needs to be done with stator disconnected. There's a total of twelve tests.

Tests 1-3) One meter lead on RED Rec/Reg wire. Test all three Yellow wires with other meter lead.
Tests 4-6) Reverse the meter leads and test all three yellow wires again.
Expected results) Should have continuity to all three yellow wires in either Tests 1-3 OR Tests 4-6 direction. A yellow wire with continuity in both direction has shorted diode to Positive rail, a yellow wire with no continuity in either direction has open diode to positive rail.

Tests 7-9) One meter lead to GREEN Rec/Reg wire. Test all three Yellow wires with other meter lead.
Tests 10-12) Reverse the meter leads and test all three yellow wires again.
Expected results) Should have continuity to all three yellow wires in either Tests 7-9 OR Tests 10-12 direction. A yellow wire with continuity in both direction has shorted diode to Negative rail, a yellow wire with no continuity in either direction has open diode to negative rail.

[joecoolsuncle]

yes, a bad regulator / rectifier absolutely can cause stator failure. heat is the enemy. when i bought my 1984 gl1200a, the yellow wires had been soldered, the stator tested bad, and i pulled the engine. the yellow wires had been hot and haad cooked way past the connection and even discolored to the grommet where they entered the stator cover! previous repair had only soldered the same damaged old wires to the new stator wires. it failed again, obviously. bad ground can also cause charging system failure.
good luck, maybe yours is not so bad and you will have a trouble free 100,000 miles!

[RadWingDad]

Before I get to testing, should the RR be tested with the engine running or no? My Clymer manual seems to say not, which is how I've been testing it. This doesn't make a lot of sense to me, but honestly, I understand electricity about as well as I understand magic.

[RadWingDad]

I couldn't wait (Lord grant me patience and I want it NOW!) for an answer so I tested the RR with the stator disconnected and the engine running at 3K RPM and then not running. Got the same results both times.

With the red lead from the multi-meter to the green wire on the RR, I got .547 or close to it on all yellow wires.
Black lead to green wire I got infinite resistance.

Red lead to red wire I got infinite resistance.
Black lead to red wire I got .537 or close to it on all yellow wires.

Stator test: Engine running at 3K RPM, stator disconnected and multi-meter set to 20VAC
Black lead from multi-meter to any wire red lead not connected to anything gave me 11VAC or close to it.
Any other combination of test leads to two yellow wires, one yellow and ground, one yellow and negative battery terminal, etc gave me a 1 like I would see when testing continuity. This is confounding, but like I said electricity=magic.

[joecoolsuncle]

I think you missed mr denver wingers post. scroll up. he has it all typed out for you. read his first sentence in that post.
maybe if you just worry about testing the stator, exactly as denver winger has stated, and do not worry about the reg/rect, then it will help simplify.

Then, remember this.........if stator is bad, replace stator AND reg/rect. if stator is good, replace reg/rect. as you can see, in either case, replace that regulator.

Also, be sure and repair the yellow wires all the way from stator to regulator.
good luck, and holler back.

[DenverWinger]

I couldn't wait (Lord grant me patience and I want it NOW!) for an answer so I tested the RR with the stator disconnected and the engine running at 3K RPM and then not running. Got the same results both times.

With the red lead from the multi-meter to the green wire on the RR, I got .547 or close to it on all yellow wires.
Black lead to green wire I got infinite resistance.

Red lead to red wire I got infinite resistance.
Black lead to red wire I got .537 or close to it on all yellow wires.

Stator test: Engine running at 3K RPM, stator disconnected and multi-meter set to 20VAC
Black lead from multi-meter to any wire red lead not connected to anything gave me 11VAC or close to it.
Any other combination of test leads to two yellow wires, one yellow and ground, one yellow and negative battery terminal, etc gave me a 1 like I would see when testing continuity. This is confounding, but like I said electricity=magic.

Engine doesn't need to be running to do Rectifier test. Doesn't matter, really. Per your results the rectifier is good.

Stator test still not being done correctly. With stator wires disconnected, put AC volt meter red lead on one yellow stator wire, the black lead on another. Read AC voltage at 3000 RPM. Repeat test twice more until you've measured all three combinations of stator wires (A-B, A-C, B-C). 50-70 volts AC expected.

One more test, with engine off measure ohms between the three yellow stator wires and ground or neg battery terminal. High or infinite resistance is expected. Then report back.

[RadWingDad]

Engine doesn't need to be running to do Rectifier test. Doesn't matter, really. Per your results the rectifier is good.

Stator test still not being done correctly. With stator wires disconnected, put AC volt meter red lead on one yellow stator wire, the black lead on another. Read AC voltage at 3000 RPM. Repeat test twice more until you've measured all three combinations of stator wires (A-B, A-C, B-C). 50-70 volts AC expected.

One more test, with engine off measure ohms between the three yellow stator wires and ground or neg battery terminal. High or infinite resistance is expected. Then report back.

OK. With the engine running at 3K RPM and the multi-meter set to 200VAC, all three combinations of yellow wires at the disconnected stator connector measured ~74V.

Resistance between the yellow wires and frame ground is infinite.

Just for kicks I measured the resistance of the wires from the stator connector to the rectifier. Got a tone and 0.02 on all three wires, which I guess indicates those wires have minimal resistance, which I interpret as a good thing.

Oh, I tested the old regulator and it tested good, as well. So I really have no idea why the battery isn't charging. The battery was replaced after the stator, so it should be good.

[DenverWinger]

OK - Looks like Stator is good too.

I'd eliminate the connector in the stator wires, and solder them instead. The connector is a known weak point on these bikes.

The Rec/Reg test confirmed the rectifier diodes are ok, but that doesn't mean the regulator portion is good.

Reconnect the stator and we'll do some more measurements. First measure battery voltage at 3000 RPM and see if eliminating that connector fixed the charging.

Then at 3000 RPM measure DC voltage between Red Rec/Reg wire and battery POS terminal. Also measure DC voltage between Rec/Reg Green wire and Battery Neg terminal. Both should be well under a volt. Measure and report back.

[RadWingDad]

Battery voltage at 3K RPM is 11.4-11.5V
Engine off it's 11.86V

Red Rec wire(s) to POS battery terminal is 2.07V
Green Rec wire(s) to NEG battery terminal is 0.05V

Either Red Rec wire to either Green Rec wire is 13.4V

[DenverWinger]

The charging system appears to be OK.

But there's a big voltage loss (2 volt difference) from the red wire at the R/R to the battery. This is supposed to be a direct connection to the main fuse just before reaching the battery and should be very nearly 0 volts. There is a bad connection somewhere between the red wires at the R/R and the Main fuse. That 13.4 volts you measured at the R/R is supposed to be charging the bike battery but it isn't getting there!

Time to start tracing the red wires to find the bad connection, or you can run new ones.

13.4 charging volts is a little bit on the low side, but is plenty enough to charge the battery. Once the bad connections are corrected that voltage may come up some.

[RadWingDad]

This is great news. I'll run new wires today. I recall seeing a connector near the battery (may have been the one that plugs in to the stater solenoid) when I was troubleshooting the starting system that looked sketchy. If I can find some yellow wire I'll probably replace the yellow wires from the stator all the way to the Regulator connector.

Thank you so much for your help. You've been very patient and thorough, which I appreciate greatly. I've always had trouble wrangling the angry pixies in electrical systems and your advice has been priceless.

[RadWingDad]

A little gift from one of the previous owners. I'm pretty sure this is the cause of the voltage drop. My guess is that this connector was never making good contact with its mate on top of the starter solenoid. Here I've pulled it out of the plastic connector. I need to pick up some wire of the correct size and replace it, then test again. I'll report back.

[WingAdmin]

Engine doesn't need to be running to do Rectifier test. Doesn't matter, really. Per your results the rectifier is good.

Stator test still not being done correctly. With stator wires disconnected, put AC volt meter red lead on one yellow stator wire, the black lead on another. Read AC voltage at 3000 RPM. Repeat test twice more until you've measured all three combinations of stator wires (A-B, A-C, B-C). 50-70 volts AC expected.

One more test, with engine off measure ohms between the three yellow stator wires and ground or neg battery terminal. High or infinite resistance is expected. Then report back.

OK. With the engine running at 3K RPM and the multi-meter set to 200VAC, all three combinations of yellow wires at the disconnected stator connector measured ~74V.

Resistance between the yellow wires and frame ground is infinite.

Just for kicks I measured the resistance of the wires from the stator connector to the rectifier. Got a tone and 0.02 on all three wires, which I guess indicates those wires have minimal resistance, which I interpret as a good thing.

Oh, I tested the old regulator and it tested good, as well. So I really have no idea why the battery isn't charging. The battery was replaced after the stator, so it should be good.

For anyone reading this and planning to do the same test on their bike, please take the same precautions on this test that you would take if working on LIVE wiring in your house. The voltages are comparable, and they are AC. That is to say, the power being produced by a healthy stator even with the engine at idle are potentially LETHAL. If you don't know exactly what you are doing when testing them, perhaps get the assistance of someone experienced with electricity.

[RadWingDad]

All tests point to everything working nominally now. I really think replacing the yellow wires from the stator connector to the regulator/rectifier connector and the red wires from there to the battery fixed the problem. I didn't write all the measurements down before I buttoned it up, but I remember the battery voltage ranging from about 12.5 to about 13.5 depending on RPMs and the voltage coming out of the regulator being about 14. There still seems to be about .5V drop from the regulator to the battery. Not sure why, but I did replace the nasty connector that goes in to the top of the starter solenoid.

[RadWingDad]

I took Old Wing out for a shakedown ride yesterday and the charging system seemed to work great. She started right up every time. It looks like we've chased the gremlins away for now. The ride ended up with a flat rear tire, but that's a story for another day. I can say my AAA membership has more than paid for itself thanks to this bike.

[DenverWinger]

Nothing like success, huh?

[joecoolsuncle]

Nothing like success, huh?

that was a great job of walking him through the diagnostics and repair!

[otisrulz]

OK, who is in Central Illinois and can come show me how to do this? I have a Multi-meter, but very little knowledge in using it. Replaced the stator in my 87 GL1200 a few years ago, and it still only charges between 13.2 and 13.7 volts.

[Rambozo]

That's a little low, but not too bad. Standard charging is 13.8 to 14.2 for lead acid battery. First thing clean up all your connectors and do the three yellow wire solder mod. then recheck and I bet you will be fine.