Testing Stator

[Chuey]

The charging system wasn't charging on the latest bike I've been working on. (1983 R100) I was able to find, by searching, a figure for testing the rotor. The way I understand it, putting one probe on each of the copper rings the brushes ride on should be somewhere around the 4ohms mine shows. So, is that enough to consider the rotor good?

Is there a test for the Stator? On this one, the cast aluminum outer housing comes loose from the windings part of the assembly. Of course, when it is bolted into position, that is not happening. I mention this in case that makes the part a no-go.

The engine, and thus the alternator parts are from a bike that had been wrecked with 34,000 miles. In other words, it has not worked or been used for quite a while. It is not a known good working set-up that has developed a problem. It is quite possible that I've put something together wrong or damaged it by cleaning it improperly.

The inside brush did not extend down out of its slot. I prodded it a bit and it is now moving freely. Before I removed the stator, the brushes both looked like they were making contact.

Main thing I need to know at this point is if there is a test for the stator.

Thanks for the help.

Chuey

[Garnet]

http://www.largiader.com/articles/charging/

According to the above 0.6 ohms is what you are looking for.

Edit: I believe you test between each of the 4 winding wires that go up to the diode board, I can't rember.

[Chuey]

Thanks for the link, Garnet. It has some values for resistance but does not tell me where to put the multimeter probes to test the stator.

When I tested the rotor, I put one probe on each of the surfaces that the brushes run on. Is that the right way? It read 4ohms.

Can somebody please say how to test the stator and what value indicates good or bad? I'm not well versed in this 'lectricity stuff and what may seem basic to some, may not be accessible to me. Thanks.

Chuey

[Deleted User 62]

Chuey, when you tested the rotor, did make sure that at least one of the brushes was not touching the slip ring?

[Deleted User 287]

I don't have the figure you are looking for Chuey, but I know stators rarely go bad, FWIW.

Regarding the stator, more than once have I read accounts of owners chasing an open circuit on one. The problem is is that they static test just fine, but when spinning the centrifugal force opens up the minute break in the winding.

Perhaps mount the rotor on a lathe for testing?

[Ken in Oklahoma]

Regarding the stator, more than once have I read accounts of owners chasing an open circuit on one. The problem is is that they static test just fine, but when spinning the centrifugal force opens up the minute break in the winding.

Rob, I believe you meant to say rotor here.


Ken

[Chuey]

I've been reading Snowbum's treatise on electricity. Here's what he said about the stator: "Stators can be tested with alternating current applied. Stators can be checked for resistance between windings, and to ground, but except for the ground type, the tests are not definitive, unless grossly wrong."

Now, consider my embarrassing but acknowledged state of mind with regards to electricity. That's right, I have no idea what that means.

The rotor was tested with the stator off the bike. In other woids, no brushes or anything else polluting the reading. I have learned that 4ohms is a tad high and it should be in the 3ohm range for this bike. I have no idea if one ohm is a deal breaker or if it is inconsequential. I'm trying. I really am.

Chuey

[Garnet]

So, I'm not the only one who can't follow what Snobum means at times.

Unplug the three wire plug that goes up to the diode from the front of the stator. Put one lead of your meter on the center spade and the other on one of the outside spades. You should see a resistance.

[Chuey]

So, I'm not the only one who can't follow what Snobum means at times.

Unplug the three wire plug that goes up to the diode from the front of the stator. Put one lead of your meter on the center spade and the other on one of the outside spades. You should see a resistance.

Is it OK if the stator is off the engine? Mine tested .9

Chuey

[Garnet]

Yes it's OK to test on the bench. And .9 means that there are no breaks in the windings and that it should be fine. The differance between what you are reading and what the spec is, is what Snobum was trying to explain.