Is my stator dead or is something else wrong?

[Ola]

A week ago my bike suddenly lost power and stopped, drained of juice. I took the battery home, charged it and rode home ok. I measured the voltage over the battery at 3-5K rpm and it did not change from idle. I then followed the excellent stator papers, sans VAC output test from stator since the multimeter I used didn't work with AC.

However, the r/r showed bad symptoms and I ordered a new one. Got it installed and when there was still no charge over the battery I admit to feelings of , and .

I got a multimeter where AC worked (confirmed with wall socket) and measured stator output. 6 volts across 1-2 and 1-3, nothing over 2-3. Sounds bad right? But the thing is there is no continuity to ground from any yellow and ohm between all yellows are spot on 0.9 ohms.

I'd like to have the failure mode properly mapped out and the faulty item properly identified before I order a new part. It could be that the old r/r was indeed broken (haven't had much time to doublecheck the new one) but it could also be that I incorrectly diagnosed a good r/r, although it failed the diode test pr the stator papers.

Isn't it fairly common to have one poor component ruin the other? That would explain a dual failure. And isn't it also a bit weird that the stator ohms fine but refuses to put out proper voltage? What could cause a good stator to display this behaviour? Since I ohm'ed it from the r/r connectors (with r/r disconnected) the wiring should be good too...

[jbs80106]

It's difficult to say 100%....

if the stator is the only problem.

If you've only got 6 volts off 2 of the legs then you've definately got a problem there. If the stator isn't generating enough voltage then the Reg/Rec won't work obviously. It's possible that your old reg/rec was okay (hopefully you kept it).

I'd order a replacement. I bought from Electrosport, and bought a used one offa ebay. The used one is currently on my bike after the electrosport one crapped out. E-sport did send me replacement on warrantee but I've not had time to install it yet...

Someone more experienced with bike electrics might chime it on your question about how the resistance on the stator can pass the test, but the voltage not.

one thought might be to pull your starter motor cover off, examine the wires from the stator to the reg/rec. Maybe you've got a short in there or something...but I'd just replace the stator....

[argonsagas]

if the stator is the only problem.

If you've only got 6 volts off 2 of the legs then you've definately got a problem there. If the stator isn't generating enough voltage then the Reg/Rec won't work obviously. It's possible that your old reg/rec was okay (hopefully you kept it).

I'd order a replacement. I bought from Electrosport, and bought a used one offa ebay. The used one is currently on my bike after the electrosport one crapped out. E-sport did send me replacement on warrantee but I've not had time to install it yet...

Someone more experienced with bike electrics might chime it on your question about how the resistance on the stator can pass the test, but the voltage not.

one thought might be to pull your starter motor cover off, examine the wires from the stator to the reg/rec. Maybe you've got a short in there or something...but I'd just replace the stator....

Skip the wondering about the reasons for the condition of the stator.

Reality says that with only 6 volts output you must replace it. Take care of that and ride the bike...wonder about the conditions over the winter.

[Ola]

I kept the old r/r. The new one is unoriginal, half price and supposedly better than stock. Don't remember the brand but Electrosport's would cost too much in shipping to Norway.

Guess I'll have to get the new stator, sigh. What really irks me is I might have replaced a good component that cost the same as the faulty component. The money is just money but me having poor troubleshooting skills when so much help is available online is and !!

[BassCliff]

Hi Mr. Ola,

The stator failed on my bike when it ran too hot for too long (possibly due to a bad r/r) and melted the insulation between the wires. Thus turning my three phase coil windings into hunks of useless metal, unable to generate alternating current. The resistance measurements all checked out, but since I had lumps of copper instead of three phases of copper wire windings, it would not generate electricity.



This stator had about 13VAC output on a couple of legs. When I looked at it, I knew why. Best of luck with your repairs.

Thank you for your indulgence,

BassCliff

[Ola]

Great failure mode example! It also includes me having correctly diagnosed the r/r as bad, I'll tear into it tomorrow and have a look-see.

[Ola]

Just a quick follow up question about the cause. I did some mig welding on the bike not too long before this happened (maybe 150 miles). The ground clamp was right next to the electrode and it was on the upper rear part of the frame, one of the bolt brackets which holds my luggage frame. I had removed the battery but not disconnected anything else electrical. Could it have caused the charging system to soil its pants?

[Ola]

Another dumb question sorry for asking so blindly, I do check out the forum thoroughly, it's just about being sure.

I took out the stator today, it did not look obviously charred. It did look black and dirty and some wires were definitely questionable, looking kind of furry. Before I could get it out completely (or take pics) and cleaned from oil I got interrupted and had to put the bike back in the garage. The dumb questions are thus: Will a bad stator be easy to see as such? Does it take a lot of charring to ruin a stator or is it gone once it starts?

I'm assuming it only takes a few shorts between each winding to ruin the coil effect.

[doctorgonzo]

Another dumb question sorry for asking so blindly, I do check out the forum thoroughly, it's just about being sure.

I took out the stator today, it did not look obviously charred. It did look black and dirty and some wires were definitely questionable, looking kind of furry. Before I could get it out completely (or take pics) and cleaned from oil I got interrupted and had to put the bike back in the garage. The dumb questions are thus: Will a bad stator be easy to see as such? Does it take a lot of charring to ruin a stator or is it gone once it starts?

I'm assuming it only takes a few shorts between each winding to ruin the coil effect.

You know it's bad by the output not visually. Mine looked fine, but was only putting out 20v AC, so I trashed it.

[BassCliff]

Hi Mr. Ola,

I don't think the stator fails so spectacularly that often. You might have some internal wiring shorted due to melted insulation while the outer coating seems intact. Like Mr. doctorgonzo said, the measurements are the determining factor.

As long as you had the battery disconnected, I don't think the welding could hurt your stator.

EDIT: Do you notice that "I don't think" very much?

Thank you for your indulgence,

BassCliff

[Ola]

Great info, I'll order a new stator now and I'll have it in two days so hopefully I'll be riding with a good charge this weeked. Thanks much!