Cooked Stator Coil

[karlhoffman_76]

Greetings, long time no post! Hope you're all thriving amidst the pandemic.

About a week ago my battery failed to charge, so thinking as simple as possible, I took it out, hooked it up the the charger, thoroughly cleaned the contacts on the battery and the bike and then hooked it back up to the bike again. After a few days, dead again.

Solenoid and starter are good, so it wasn't a case of a faulty starter circuit, and multimeter again confirmed 11.5 V on the battery. So this time I checked both the stator coil and reg/rec.

Charging load test gave ~10V and dropping at the battery. A reg/rec diode test revealed 0.5 V in forward bias on both output terminals and open circuit in reverse bias on both output terminals, so all good there. Stator coil no-load test was giving ~10 V and dropping on all three windings at ~4k RPM, so pretty certain it is the culprit. A continuity test on the stator revealed continuity between each winding and open circuit between each terminal and ground. I also checked the stator side wiring between the connector and the rubber stop in the stator cover, and whilst there was some breaks in the wiring insulation, there was absolutely nothing shorting there. So I believe there must be a short or two in the coil itself.

Here's the kicker though; I bloody well changed it out just over two years ago, using a new ElectroSports aftermarket coil! So before I go purchasing a new one, I was wondering what you guys would recommend in terms of brand and price, bearing in mind I live in Sydney, Australia. I am actually livid about the fact that I spent upwards of AUD 200 for a new coil, only for it to drop it's guts only 25k kms and two years later. Not to mention the giant pain in the arse it is to replace it, WTF?!

I get that it's supposed to be a cheap bike, but goddamn.

Any and all suggestions appreciated, thanks in advance!

[SK Racing]

I would rewind it. Magnet wire is not that expensive and rewinding not difficult. Our local bike shop rewinds stators all the time.

If you need help with figuring out the winding scheme, number of turns and wire thickness, drop me a line by PM.

[mentalshark]

You may want to check how the stator is damaged. With my limited knowledge in electrical stuff, if the stator is not damaged by physical impact, then there is a chance there is something in your bike's electrical system that had caused the stator coil to fry. When a coil is fried it's caused by excessive heat, this could be caused by a number of things: dangling wire, lose connection, short in the wire harness. on a side note, the diode test can also test the rectifier part of the r/r system, the regulator part cant be tested with a multimeter.

also, what is the resistance reading of the 3 coils?

[Bluesmudge]

I get that it's supposed to be a cheap bike, but goddamn.

Cheap to buy and cheap to work on...but you never stop working on it so it all adds up!

Have you considered changing the regulator/rectifier with a more modern one? I've heard that a bad R/R can cook the stator, so replacing just the stator again is just punting the issue down the road for a few more miles.

[HPP8140]

I get that it's supposed to be a cheap bike, but goddamn.

Cheap to buy and cheap to work on...but you never stop working on it so it all adds up!

Have you considered changing the regulator/rectifier with a more modern one? I've heard that a bad R/R can cook the stator, so replacing just the stator again is just punting the issue down the road for a few more miles.

Agree...just need to hold it straight wile pushing down

[HPP8140]

sorry wrong thread

[karlhoffman_76]

I would rewind it. Magnet wire is not that expensive and rewinding not difficult. Our local bike shop rewinds stators all the time.

If you need help with figuring out the winding scheme, number of turns and wire thickness, drop me a line by PM.

Yeah could be the go for next time. I think I'll buy a new coil and then rewind the old one when I get the time. I'll hit you up at some point in the future, cheers!

You may want to check how the stator is damaged. With my limited knowledge in electrical stuff, if the stator is not damaged by physical impact, then there is a chance there is something in your bike's electrical system that had caused the stator coil to fry. When a coil is fried it's caused by excessive heat, this could be caused by a number of things: dangling wire, lose connection, short in the wire harness. on a side note, the diode test can also test the rectifier part of the r/r system, the regulator part cant be tested with a multimeter.

also, what is the resistance reading of the 3 coils?

Resistance is measuring 1.2 ohm on all three windings and open circuit to ground. I mean it's entirely possible that the regulator is cooked and not bleeding off enough voltage from the rectifier, but then you might expect the battery to be cooked as well as a result. I might change out the reg/rec just to be sure.

I get that it's supposed to be a cheap bike, but goddamn.

Cheap to buy and cheap to work on...but you never stop working on it so it all adds up!

Have you considered changing the regulator/rectifier with a more modern one? I've heard that a bad R/R can cook the stator, so replacing just the stator again is just punting the issue down the road for a few more miles.

I actually have an '07 ZX6R reg/rec, the one I've seen a few people talk about using. I might swap it in then and see how it goes.

Do you guys have any suggestions for aftermarket coils? I think I'll just get the ElectroSports coil again, barring any suggestions.

[The Buddha]

A burnt stator will have some spots atleast that are black and crusty.
Cool.
Buddha.

[SK Racing]

Stator coil no-load test was giving ~10 V and dropping on all three windings at ~4k RPM, so pretty certain it is the culprit. A continuity test on the stator revealed continuity between each winding and open circuit between each terminal and ground. I also checked the stator side wiring between the connector and the rubber stop in the stator cover, and whilst there was some breaks in the wiring insulation, there was absolutely nothing shorting there. So I believe there must be a short or two in the coil itself.

It's actually very easy to test a stator. All three phases should have more or less the same resistance when measured in Ohms with a multimeter. If there is a short, it will show up as less resistance in one or two phases. Also, the phases should have no continuity to the metal laminations. If it passes this test, there is probably nothing wrong with the stator and windings.

The resistance of the windings should ideally be measured via the Kelvin 4-wire method (see link below), but a multimeter test should be able to point out any problems.

http://bavaria-direct.co.za/constants/#Rm

[karlhoffman_76]

A burnt stator will have some spots atleast that are black and crusty.
Cool.
Buddha.

Yeah, I guess I will potentially see that when I swap it out. I will report my findings.

Stator coil no-load test was giving ~10 V and dropping on all three windings at ~4k RPM, so pretty certain it is the culprit. A continuity test on the stator revealed continuity between each winding and open circuit between each terminal and ground. I also checked the stator side wiring between the connector and the rubber stop in the stator cover, and whilst there was some breaks in the wiring insulation, there was absolutely nothing shorting there. So I believe there must be a short or two in the coil itself.

It's actually very easy to test a stator. All three phases should have more or less the same resistance when measured in Ohms with a multimeter. If there is a short, it will show up as less resistance in one or two phases. Also, the phases should have no continuity to the metal laminations. If it passes this test, there is probably nothing wrong with the stator and windings.

The resistance of the windings should ideally be measured via the Kelvin 4-wire method (see link below), but a multimeter test should be able to point out any problems.

http://bavaria-direct.co.za/constants/#Rm

Well, if I'm only getting 10 VAC on each winding under stator no-load test at around ~4k RPM and there are no shorts to earth, seems to me the coil itself is the only thing left to consider, unless I'm missing something. I know the no-load test is supposed to be done at 5k RPM, but I would expect to see a lot more than 10 V at 4k RPM if it was functional.

[herennow]

Just a quick question, are you using a good multimeter. Cheap ones can be very dodgy around running bikes. Just a thought. Been there done that!

[karlhoffman_76]

Just a quick question, are you using a good multimeter. Cheap ones can be very dodgy around running bikes. Just a thought. Been there done that!

Hmmm, yeah that's certainly a possibility, I only have a $50 Digitor (D*ck Smith) DMM, so maybe stator output is not being measured correctly. Regulator output is definitely kaput though, I know because I have measured the correct DC voltage using the same multimeter in a battery load test in the past. Could it really be out by 50 or 60 odd volts though?

Edit: Just ordered a new Fluke 17B+ from ebay, figured it's a good idea to have a good multimeter at any rate. Also, when I said battery load test I meant charging load test.

[Bluesmudge]

$50!?? Does this mean my $7 multimeter from harbor freight is not a "good" multimeter? 

[karlhoffman_76]

$50!?? Does this mean my $7 multimeter from harbor freight is not a "good" multimeter? 

Lol, well it would be interesting to compare to see what the difference is between them. I'm guessing there won't be much difference at all between the Fluke and Digitor DMMs, but I could be wrong. I did some searching around and the consensus seemed to be to get a multimeter around the $150 mark.

[The Buddha]

I have both - in fact I have a $1700 fluke German or swiss big yellow beast like 1/2 a brick, that was $1700 in ~1990 which would be right about $3,000 or more now. It weighs as much as a hammer and has all discrete circuits and build rugged as a tank.
But, now in 1990's it was built for linemen to climb up telephone poles and have it survive a drop, survive getting hit with million volts getting rained on etc etc. Nice big lettering, good click click control.
Accurate yes, but no more so than the $7 HB from last year. But try clocking your stupid apperentice on the head with that one and you'd make a hilarious wet noodle "thip" noise. The computing power from a million circuits are now in 1 tiny chip. Hence the little one works fine, but the controls, the lettering etc etc would be far inferior. Is it worth the 500X or more cost difference - well that depends on how stupid your apparentice is.

Cool.
Buddha.

[karlhoffman_76]

I have both - in fact I have a $1700 fluke German or swiss big yellow beast like 1/2 a brick, that was $1700 in ~1990 which would be right about $3,000 or more now. It weighs as much as a hammer and has all discrete circuits and build rugged as a tank.
But, now in 1990's it was built for linemen to climb up telephone poles and have it survive a drop, survive getting hit with million volts getting rained on etc etc. Nice big lettering, good click click control.
Accurate yes, but no more so than the $7 HB from last year. But try clocking your stupid apperentice on the head with that one and you'd make a hilarious wet noodle "thip" noise. The computing power from a million circuits are now in 1 tiny chip. Hence the little one works fine, but the controls, the lettering etc etc would be far inferior. Is it worth the 500X or more cost difference - well that depends on how stupid your apparentice is.

Cool.
Buddha.

Haha, well, better safe than sorry I guess. I take it you've had a few apprentices then? It all adds up over time, the satisfying "thip" sound is a bonus. I doubt I would ever spend $3000 on a multimeter though personally. Sounds like the kind of thing you will pass down to your children and children's children lol

[The Buddha]

No apparentices really, some ocassional owners of bikes or electronics wanting me to repair stuff as well as bikes saying stupid stuff.

One clown was going on and on about how his amp was all copper chassis and all copper hardware as I was unscrewing the screws and what not with a magnetic screwdriver and handing it to him. After I did that 50 times. To take the bottom plate off no doubt all of it was copper colored ... instead of taking it off by hand, I elaborately used my stack of neo magnets to "lift" it out.

I then asked him, you know what metals stick to magnets right ... and he took like 5 mins of blinking like I turned his copper into steel right in front of him.
Yea pioneer painted all of it copper colored in their "high end" crap.

Cool.
Buddha.

[herennow]

Super happy with my fluke 115, Although I keep a good stock of the big fuses on hand , I occasionally do dumb things.😉
I've seen dozens of cases where cheap meters do wierd things, especially on running bikes, they can't handle the electrical noise.
Enjoy the new meter!

[karlhoffman_76]

No apparentices really, some ocassional owners of bikes or electronics wanting me to repair stuff as well as bikes saying stupid stuff.

One clown was going on and on about how his amp was all copper chassis and all copper hardware as I was unscrewing the screws and what not with a magnetic screwdriver and handing it to him. After I did that 50 times. To take the bottom plate off no doubt all of it was copper colored ... instead of taking it off by hand, I elaborately used my stack of neo magnets to "lift" it out.

I then asked him, you know what metals stick to magnets right ... and he took like 5 mins of blinking like I turned his copper into steel right in front of him.
Yea pioneer painted all of it copper colored in their "high end" crap.

Cool.
Buddha.

That is quite hilarious actually. I'm sure he won't forget that anytime soon, haha.

Super happy with my fluke 115, Although I keep a good stock of the big fuses on hand , I occasionally do dumb things.😉
I've seen dozens of cases where cheap meters do wierd things, especially on running bikes, they can't handle the electrical noise.
Enjoy the new meter!

Thanks, will do. Like I said above, my guess is there won't be much difference here, but yeah, could be wrong. It's good to have a standard candle, as it were, to gauge against.

[karlhoffman_76]

Changed out the stator coil today but double checked the old coil again before removing it. My new Fluke DMM was giving me ~10VAC on each winding at ~4k RPM, which I kind of expected anyway. Turns out my Digitor DMM is fairly accurate. New coil is in as I speak, and I'm leaving it overnight so that the liquid gasket can set against the rubber coil plug. Will test it in the morning. This is what the old coil looked like btw, there's some slight discoloration at the top of the stator in the first pic, perhaps that is where it was shorting?

https://scontent.fsyd8-1.fna.fbcdn.net/v/t39.30808-6/240403606_10159578606114106_5074399341635676185_n.jpg?_nc_cat=100&ccb=1-5&_nc_sid=0debeb&_nc_ohc=plYPyHogjpEAX-R-oEl&_nc_ht=scontent.fsyd8-1.fna&oh=6243c2d29e1fc92a03167ff6aeb67b0f&oe=612F139D

https://scontent.fsyd8-1.fna.fbcdn.net/v/t39.30808-6/240000868_10159578606084106_6791068090617673518_n.jpg?_nc_cat=103&ccb=1-5&_nc_sid=0debeb&_nc_ohc=zvRSTwkkXzQAX_zloQc&_nc_ht=scontent.fsyd8-1.fna&oh=f3e3d0de03c4b3b3eff5fdc9a494d172&oe=612ED4DA

https://scontent.fsyd8-1.fna.fbcdn.net/v/t39.30808-6/240119354_10159578606244106_8140442422911564746_n.jpg?_nc_cat=102&ccb=1-5&_nc_sid=0debeb&_nc_ohc=Pn196q6K5fcAX-SY49e&_nc_ht=scontent.fsyd8-1.fna&oh=2c7de4979b02bd6c8f7acfc14296aa3d&oe=61300012

https://scontent.fsyd8-1.fna.fbcdn.net/v/t39.30808-6/240594025_10159578606224106_3878645989241650326_n.jpg?_nc_cat=111&ccb=1-5&_nc_sid=0debeb&_nc_ohc=N3gdEM5A3sgAX-eZSBw&_nc_ht=scontent.fsyd8-1.fna&oh=ada95fb69a11bc06bc98d1d154f9c922&oe=612FE393

I've also wired up an '07 ZX6R reg/rec to replace the stock one. I cut the leads off the stock reg/rec and crimped them to the ZX6R reg/rec wires, that way I don't have to worry about replacing the connectors. Diode test looks good in forward and revers bias, so fingers crossed this will be a significant upgrade. Pics below show it in more detail;

https://scontent.fsyd8-1.fna.fbcdn.net/v/t39.30808-6/240227305_10159578606054106_8815808005836075874_n.jpg?_nc_cat=101&ccb=1-5&_nc_sid=0debeb&_nc_ohc=skDleDQQXtgAX8J38NI&_nc_ht=scontent.fsyd8-1.fna&oh=98a3250514a5cc51b92bf84b19cd7777&oe=612FB82B

https://scontent.fsyd8-1.fna.fbcdn.net/v/t39.30808-6/240452343_10159578606004106_8721367990817382287_n.jpg?_nc_cat=109&ccb=1-5&_nc_sid=0debeb&_nc_ohc=GRU4qzvn25MAX8XdkD2&_nc_ht=scontent.fsyd8-1.fna&oh=2b079e7f444c46fb5aefcbde62226f0f&oe=612E5300