would you replace a stator with these readings?

[don_gibb6512]

Looks like I'm going to pull the stator and take it to our lab for further testing. Better safe than sorry. I'll post the results, probably at the end of next week.

[bakalorz]

Yes but I am getting 64v AC out of the stator at 5K rpm's though. The fact that I'm getting resistance through the winding yet AC output is odd at best.

Actually thats not odd.

When its not connected to the R/R, the stator floats with respect to ground.
A short to ground in the stator (or stator connection wires) won't prevent the windings from making voltage relative to each other (which is the 64 V ac measurements)

However, when the R/R is connected, the short to ground would then cause problems, since the stator is no longer floating.

If you can find a pinched wire or whatever else is grounding out your stator, you can fix it, otherwise you will need a new stator.

---

BTW, doing Graham's test, and measuring the voltage generated between the stator connections and ground with the bike running (and the stator disconnected from the R/R) can help track down where the short likely is:

If you get three equal readings (likely to be sin(60)*64= 55 volts) then the short is probably where the three connectors join to make a Y.

If you get two readings of 64 volts and one of Zero, than the short is on the output of the winding reading zero (quite possibly where it exits the engine)

In either of these cases, it's probably possible to repair the stator without rewinding it.

If you get two high but equal readings and one that is much lower (but not almost zero) then it is probably in the middle of a winding.

In this last case it's probably NOT possible to repair the stator without rewinding it.

[bonanzadave]

Looks like I'm going to pull the stator and take it to our lab for further testing.

If the Stator is putting out why pull it ?

I'm NOT an electrical engineer

You dont need to be. There are 3 combination of stator wires to check. If you get good AC voltage on all 3 combinations youre golden. Stator wires must be completely disconnected from the RR wires / connectors and I would cut off any connectors on them to do the test. Clip the meter leads on 2 of the 3 stator wires.

wires A to B = 65VAC @ 5K RPM

wires B to C = 65VAC @ 5K RPM

wires A to C = 65VAC @ 5K RPM

[Matchless]

When its not connected to the R/R, the stator floats with respect to ground.
A short to ground in the stator (or stator connection wires) won't prevent the windings from making voltage relative to each other (which is the 64 V ac measurements)

However, when the R/R is connected, the short to ground would then cause problems, since the stator is no longer floating.

If you can find a pinched wire or whatever else is grounding out your stator, you can fix it, otherwise you will need a new stator.

This is correct!! And can cause a lot of confusion...!

[don_gibb6512]

This is correct!! And can cause a lot of confusion...!

Confusion is right. I think I'm going to order a new stator but I'm still going to take the one I've got in to our lab for further testing.

Thanks much.

[posplayr]

Confusion is right. I think I'm going to order a new stator but I'm still going to take the one I've got in to our lab for further testing.

Thanks much.

When it comes to stator tests, anything short of a loaded test (measuring current or voltage at 5K RPM) is circumstantial at best.

[mrbill5491]

My two cents.

Just reading the threads about the stator and RR unit, Posplar is no way wrong, he has some of the best replacement instructions I've seen in the forum. I should know. I have replaced my stator 7 times now and 3 RR units on my 1980 GS750E. Most of the problem was crappy replacement parts to begin with, I would only get about 3 years max off a system before it burned out. The last time I replaced them I used the Electrix's stator and RR unit, this one lasted for about 8 years for once till this last burn out. I then followed Posplar's recommendations with the Compu-Fire series type RR and a new electrosport stator and did his recommended wiring, I saw an difference right off off the bat, the wiring and RR unit were way cooler then I have ever seen them in the 30 years of owning the bike. I know for a fact if the stator is only putting out 65VAC its time to change that sucker, it is starting to die, a new one will be throwing a charge of 75-80 VAC and replace the RR unit with the Compu-Fire, remember you get with you pay for.

[tom203]

Actually thats not odd.

When its not connected to the R/R, the stator floats with respect to ground.
A short to ground in the stator (or stator connection wires) won't prevent the windings from making voltage relative to each other (which is the 64 V ac measurements)

Let's see if I'm following this "float". What you're saying is that a stator wire could be grounding out, but when we measure between any two stator leads, we don't notice this cuz we're not measuring between a stator wire and the ground. OK, makes sense. So we can't just rely on a decent ac output test of 60 volts on all 3 stator leads- we have to ohm check the stator to ground.

[don_gibb6512]

Well, I'm going with Duane's RR and an Electrosport stator. Our lab can test the stator under load (current applied) so we'll see what comes of that. It may be that the Stator papers need an appendix to accommodate situations like what I've run in to. If so, I will humbly request as such from Mr. Posplayr.

[posplayr]

Well, I'm going with Duane's RR and an Electrosport stator. Our lab can test the stator under load (current applied) so we'll see what comes of that. It may be that the Stator papers need an appendix to accommodate situations like what I've run in to. If so, I will humbly request as such from Mr. Posplayr.

I really can't take too much credit for the Phase B (stator tests) and Phase C (R/R tests) parts of the stator pages. I only modified the Phase A. However, we have had a few instances in the last couple of years where people have run into stator issues where they try to apply the stator tests and they get confusing of false results and end up wasting a bunch of time. I think it was Psyguy who had a temperature dependent stator problem he wrestled with for quite a a while before he finally just changed the stator and got over it.

So while there are so die hards (who will want to use an ohm meter even though it really is a not a good choice), it may be that the best test solution for a stator is really to just :

a.) test the R/R instead (to rule it out)

or

b.) replace the R/R with a know good (also to rule it out)

and go back to the start of the stator pages and if the problem persists change the stator.


The reality for stator is as I posted before most of the stator tests are circumstantial. Few of the tests are conclusive if all you have is a AC volt meter and a ohm meter.

When I have time I'll try and look at rewriting the other phase to reflect these realities. Swapping parts can be just as effective as testing for a defective unit and in the case of the stator actually much better to just swap parts.

[Graham]

Confusion is right. I think I'm going to order a new stator but I'm still going to take the one I've got in to our lab for further testing.

Thanks much.

Good idea.

[Matchless]

Let's see if I'm following this "float". What you're saying is that a stator wire could be grounding out, but when we measure between any two stator leads, we don't notice this cuz we're not measuring between a stator wire and the ground. OK, makes sense. So we can't just rely on a decent ac output test of 60 volts on all 3 stator leads- we have to ohm check the stator to ground.

Not really, because the AC wires are disconnected when doing the AC voltage test the leg to ground can still be measured, but is then going nowhere and the voltage test may seem to be correct. Once you plug in the AC wires then that ground forms a circuit which is common to the ground on the Rectifier/Regulator and the problems starts.

[posplayr]

If you get three equal readings (likely to be sin(60)*64= 55 volts) then the short is probably where the three connectors join to make a Y.

.

I'm starting to wonder if some manufacturers are not manufacturing with a grounded neutral got Y wound stators.

As long as the Y is balanced , a grounded neutral would have no effect because it is basically close to ground. The situation becomes unbalanced if each winding is not the same and produces different voltage or during the regulation phases of the R/R.

[bakalorz]

I'm starting to wonder if some manufacturers are not manufacturing with a grounded neutral got Y wound stators.

I really doubt it, and would hope not, because they definately wouldn't work

As long as the Y is balanced , a grounded neutral would have no effect because it is basically close to ground. The situation becomes unbalanced if each winding is not the same and produces different voltage or during the regulation phases of the R/R.

The part I made red is absolutely not true. The neutral is exactly as far from ground as it is from positive. (It bounces around near the middle between the two depending on the legs phase relationships at the time, behavior is also slightly different during regulation, but basically still holds)

[bakalorz]

I really can't take too much credit for the Phase B (stator tests) and Phase C (R/R tests) parts of the stator pages. I only modified the Phase A. However, we have had a few instances in the last couple of years where people have run into stator issues where they try to apply the stator tests and they get confusing of false results and end up wasting a bunch of time. I think it was Psyguy who had a temperature dependent stator problem he wrestled with for quite a a while before he finally just changed the stator and got over it.

So while there are so die hards (who will want to use an ohm meter even though it really is a not a good choice), it may be that the best test solution for a stator is really to just :

a.) test the R/R instead (to rule it out)

or

b.) replace the R/R with a know good (also to rule it out)

and go back to the start of the stator pages and if the problem persists change the stator.


The reality for stator is as I posted before most of the stator tests are circumstantial. Few of the tests are conclusive if all you have is a AC volt meter and a ohm meter.

When I have time I'll try and look at rewriting the other phase to reflect these realities. Swapping parts can be just as effective as testing for a defective unit and in the case of the stator actually much better to just swap parts.

I'll disagree with a lot of this.

A philosophy of just randomly swapping parts trying to "get it fixed" is a pretty poor way of trying to repair things in general.
Much better to actually diagnose what is wrong and then fix that

In particular for the electrical system on GS's there are a couple of problems with just swapping stuff:
1) the parts are relatively expensive (especially compared to the value of the whole bike) to where a couple of swaps cost more than the whole bike is worth even if you get it running perfectly. (do you really expect the average GSer to spend $300 in parts to possibly get a $500 bike running right (with no guarantee that it even will after that))
2) A lot of our problems tend to be degraded connections somewhere.
Swapping everything out wont cure any of that, unless you get lucky and fix the connection during the swap (in which case you wasted a lot of money)

Regarding the stator testing specifically; while no test can tell you that you have a good stator, the various tests can definately find bad ones.

The 60 volt AC test will definately find some stators that are defective
(probably turn to turn shorts inside.)

The ohm test WILL find any that have an open (either internally or in the connections to-from) (BTW, given the difficulty accurately measuring the phases with the average multimeter, the criteria could well be changed to: less than (say) 10 ohms and the three phases should be roughly equal (within say 20-30 percent) (of all the tests, this one could possibly be dropped ... but even then, its easy enough to do, and can rule a stator as bad)

And finally, the resistance to ground will find any (such as in this very case being discussed here) which are shorted to ground. Which definately MUST be repaired or replaced. (and FWIW, a resistance to ground measurement is ALWAYS, ALWAYS, ALWAYS part of the testing for generators and motors in the real world in industry, dropping it from the stator papers would be ludicrous and irresponsible)

---

Are there stators that will pass all these tests, but still be defective (like Psyguys) and the only way to find it is swapping ... sure, it can and does happen.

So sometimes you get through the chart and nothing makes sense, and the only way to fix it is to start swapping parts randomly till you hopefully fix the problem ...

... but leave that as the absolute last resort when you've tried everything and can't find anything, not the _default_ because its too complicated to actually troubleshoot.