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would you replace a stator with these readings?

  • Thread starter Thread starter don_gibb6512
  • Start date Start date
Hi,

Your stator:

attachment.php


If the external epoxy is bubbled like that, chances are that the insulation has melted off the windings. This is not good for stators and other living things. ;)

Here's a shot of one of my stators.

p5250014.jpg



Thank you for your indulgence,

BassCliff
 
BassCliff said:
Hi,

Your stator:

attachment.php


If the external epoxy is bubbled like that, chances are that the insulation has melted off the windings. This is not good for stators and other living things. ;)

Here's a shot of one of my stators.

p5250014.jpg



Thank you for your indulgence,

BassCliff
Click to expand...

Yes Cliff, quite obviously another case of chemical breakdown.
 
I'm having a similar problem. I get good voltage across all three legs 70 volts. Stator wires to ground 1.0, .5 and 1.0 ohms . Ohms across the legs .9 on all three. Meter set to 200 ohms for testing.

Here are my R/R tests. New R/R on order.

moz-screenshot-35.png

Regulator/Rectifer Tests ? 10/22/2010
Yellow White/Red White/Blue Forward Bias: Top 3 Diodes 0.751 0.789 0.758 Reverse Bias: Top 3 Diodes Overage Overage 1.362



Forward Bias: Bottom 3 Diodes 0.770 0.764 0.775 Reverse Bias: Bottom 3 Diodes Overage Overage Overage



* Meter set to Diode Mode (2k Ohms)
 
Last edited:
081dbx64 said:
I'm having a similar problem. I get good voltage across all three legs 70 volts. Stator wires to ground 1.0, .5 and 1.0 ohms . Ohms across the legs .9 on all three. Meter set to 200 ohms for testing.

Here are my R/R tests. New R/R on order.

moz-screenshot-35.png

Regulator/Rectifer Tests ? 10/22/2010
Yellow White/Red White/Blue Forward Bias: Top 3 Diodes 0.751 0.789 0.758 Reverse Bias: Top 3 Diodes Overage Overage 1.362



Forward Bias: Bottom 3 Diodes 0.770 0.764 0.775 Reverse Bias: Bottom 3 Diodes Overage Overage Overage



* Meter set to Diode Mode (2k Ohms)
Click to expand...
Hopefully, you have followed this saga of don's and enjoyed the experience. I'm immediately suspicious of diode readings like yours since most old diodes would forward bias at about .66 volt- newer ones maybe at .60 volt. Are your connections clean? "meter set to diode mode" ? does your meter have a seperate diode check position?
 
I went through every connection in the harness cleaned them. Meter set to diode mode.

Ya know..the bike is 30 years old. Had to replace the igniter last year..

Don't know what to think about my stator..but for a $100 bucks or so..I'm just going to replace it. It's a time vs money issue at this point. And while the part is off I might as well polish my side cover. At least now I will have peace of mind that all of the charging and ignition parts are replaced.
 
081dbx64 said:
I went through every connection in the harness cleaned them. Meter set to diode mode.

Ya know..the bike is 30 years old. Had to replace the igniter last year..

Don't know what to think about my stator..but for a $100 bucks or so..I'm just going to replace it. It's a time vs money issue at this point. And while the part is off I might as well polish my side cover. At least now I will have peace of mind that all of the charging and ignition parts are replaced.
Click to expand...
Yes , if you feel those meter readings are accurate, your stator is gone! If you can, take a pic of your old stator and post it . Peace of mind is always a good target!
 
Well, my cats think the stator is bad. I put the stator in a Kroger bag and left it on my workbench and they peed all over it last night. Good grief.
 
Well, that's it, the stator is bad. Why didn't you tell us you had cats to tell you about the stator, it would have saved us all a lot of aggravation.
 
tkent02 said:
Well, that's it, the stator is bad. Why didn't you tell us you had cats to tell you about the stator, it would have saved us all a lot of aggravation.
Click to expand...

I'll have to put the cat diagnosis option into the stator pages, for those that he them.
 
Test results.

With stator removed from the case cover, re-tested the resistance wire-wire and wire-ground: 3.64 ohms on all readings. Basically the same results as the prior two tests. For the sake of clarity, I'm going to refer to the wires as W1, W2 and W3.

Using a Variac Transformer http://www.variac.com/

W1-W2: up to 2.5 amps, meter reads 1.5v AC @ 60 cycles
W2-W3: up to 2.5 amps, meter reads 1.5v AC @ 60 cycles
W1-W3: just prior to 2.0 amps, current spikes blowing fuse in Variac

WOW!!! Short is confirmed. Wasn't expecting it to be so drastic, but yeah. I will also post an unusual picture of the stator poles. Three of them have damage to their surface which leaves me a bit concerned about clearance to the rotor surface.

Don
 
don_gibb6512 said:
Test results.

With stator removed from the case cover, re-tested the resistance wire-wire and wire-ground: 3.64 ohms on all readings. Basically the same results as the prior two tests. For the sake of clarity, I'm going to refer to the wires as W1, W2 and W3.

Using a Variac Transformer http://www.variac.com/

W1-W2: up to 2.5 amps, meter reads 1.5v AC @ 60 cycles
W2-W3: up to 2.5 amps, meter reads 1.5v AC @ 60 cycles
W1-W3: just prior to 2.0 amps, current spikes blowing fuse in Variac

WOW!!! Short is confirmed. Wasn't expecting it to be so drastic, but yeah. I will also post an unusual picture of the stator poles. Three of them have damage to their surface which leaves me a bit concerned about clearance to the rotor surface.

Don
Click to expand...
Well, I bet posplayr will rather explain this than the cat intuition stuff.
 
Anyone ever have this happen? Those were the only 3 poles with damage as far as I could tell. I'll look at them closer this evening with a magnifying glass and if weather permits, I'll inspect the rotor.
 
tom203 said:
Well, I bet posplayr will rather explain this than the cat intuition stuff.
Click to expand...

These results show the inherent problems with trying to perform unloaded tests on a stator. None of the tests that you perform using a simple VOM, are tests to positively confirm something is good. They can only be used to confirm something is bad.

For example, if you measure 70 volts AC on the stator open loop at 5K RPM you might think it is OK and the Stator is good, WRONG if it was also grounded the it would be bad. On the other hand if you measured only 25 volts, that confirms it is bad. So it can only verify a bad stator, leaving several possibilities on bad stators continuing to test good. Or a more often result is you are getting 70 volts, and there is also no short shown from the ohm meter. The you load the stator by pushing current through it, it heats a little pushes couple of oil molecules over and you have a short even though both the open loop voltage and resistance both supposedly passed.

The break down in insulation is not a simple relationship and it is a function of how much voltage you apply to the stator. An ohm meter test only applies a few volts and it may appear fine, but as soon as you raise the voltage the insulation breaks down and you have a short. The ohm meter just is not a good insulation breakdown test.

The best tests are loaded tests. That is why I modified the original stator pages phase 1 to measure the voltage drops at 5K rpm (full load) as they were originally only done at idle when there was little to any current being pushed to the battery.

The problem with doing loaded tests on the stator is you need some special AC test equipment like an oscilloscope or an AC current clamp; most people don't have these. Here is a reasonable alternative if it does what it says. BK are a reasonable economy brand of test equipment.

http://www.bkprecision.com/products/model/312B/mini-ac-milli-amp-clamp-meter-600a.html

You would basically clamp this onto one of the stator winding rev to 5K and note the AC current. Do the same think on all the phases and make sure they are balanced. I posted the average currents as a function of RPM in that Compufire SERIES R/R appraisal (both SHUNT and SERIES).


http://www.thegsresources.com/_forum/showthread.php?t=161397

SHUNT_vs_SERIES_RR_Compare_Tutorial
 
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bonanzadave said:
Looks like the bike got dumped. Ground through the side cover :-k.
Click to expand...

Good guess but that didn't happen here. I bought this stator new from Electrosport about 8 years ago and both bikes I've had this in were never in any accidents.

If the rotor turns out to be slightly worn down on one edge, will that effect it adversely in any way?
 
Any contact in there is detrimental so I would suspect foreign objects stuck to the magnet and went for a quick ride in there. Smacking the poles can cause problems, especially if the pole cracks

Take a magnet to the underside and maybe check the pan.
 
posplayr said:
The problem with doing loaded tests on the stator is you need some special AC test equipment like an oscilloscope or an AC current clamp; most people don't have these. Here is a reasonable alternative if it does what it says. BK are a reasonable economy brand of test equipment.

http://www.bkprecision.com/products/model/312B/mini-ac-milli-amp-clamp-meter-600a.html

You would basically clamp this onto one of the stator winding rev to 5K and note the AC current. Do the same think on all the phases and make sure they are balanced.
Click to expand...
Jim, I think using one of those could produce erratic results.

I used a cheap HF inductive AC ammeter when testing the current draw on my air conditioner and unless I placed the wire in the same spot in the clamp and held away from the other leg, it produced differing results. that is not to say the BK clamp will do any worse or better than the HF, just stating the results I saw.

could it have been caused by the clamp opening being a lot larger than the one used with your scope?

just saying...
 
rustybronco said:
Jim, I think using one of those could produce erratic results.

I used a cheap HF inductive AC ammeter when testing the current draw on my air conditioner and unless I placed the wire in the same spot in the clamp and held away from the other leg, it produced differing results. that is not to say the BK clamp will do any worse or better than the HF, just stating the results I saw.

could it have been caused by the clamp opening being a lot larger than the one used with your scope?

just saying...
Click to expand...

I don't know, my current clamp was $500 so it is not likely that a $85 device will even come close.

At best we can test for consistency between the windings. Maintaining consistent spacing would probably be the most fruitful. Maybe putting a foam block with a slit inside of the clamp to maintain a consistent distance for comparing the windings.
 
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