The Next Nerobro's HowTo: Doing the Stator Dance

[Nerobro]

There go the sidecovers, the tank, and suddenly the bike doesn't look so stately anymore. Poor GS. Beneath the cable tires on the center tubes, you can see the junction where the stator makes it's connection to the wiring harness. Honestly I don't like the setup much. 20amps go up some fine wires to those connections, then down the wiring harness, and under the battery, and up behind the battery, to the r/r. I'm going to be moving the r/r to somwhere it'll get airflow.. soon.

Skreemer, working on getting into the stator cover. He'd already gotten the starter cover off. The bike is leaning on the doorjam. By leaning the bike over you can gain access without having to drain the oil. I put the bike in first before I leaned it over so it is being held in place.

Can you guess where the stator wires go?

Can you guess now? The big thing on the end of the crankshaft is the rotor. The "misplaced" gear is the reduction gear for the starter. The shaft it normally rides on is still stuck in the stator cover. This is where we discovered that this bike has had it's stator replaced before.

 

[Nerobro]

The stock fasteners for the stator are Phillips head screws. Those, are not, Phillips head. The retaining clip is also an allen head, and that too is supposed to be a Phillips head screw. So along with being on at least it's third r/r, this will be at least it's third stator. Speaking of which, you can really see the damage on that stator. I blame it's condition on a failed gsxr r/r that I installed on the bike. There are certain r/r failures that are very hard to bench test, and I obviously missed a shot SCR. I'll be doing an autopsy on it later.

Though you can't read the numbers on that DVM, it's reading 90 volts. Which is certainly acceptable. At least it's better than the 45 I was getting before. That means I succeeded.


We put an hours worth of riding on the bike today. The solder joints are holding, and the battery is charging to 13.3 volts. Which is acceptable.

Yet another home spun fix. That appears successful.

 

[cberkeley]

Excellent ....way to go!

 

[Boondocks]

Very nice work competently performed, Nerobro.

This info and pictures will be very useful for those that want to rewind their own stators. This would make a very good addition to the stator papers.

 

[80gs1000e]

Yup, I did this all at my desk at work. On the clock...

...... :lol:

 

[HammerHead]

An Awesome feat.
Definitely a tread that we will all be comming back to time and time again. Thanks to individuals like yourself, this forum ROCKS!!!

 

[skreemer]

as a little end to the tale we ran the bike around for a bit in a parking lot... Everything worked like a charm.

We also took our new roommate out to the parking lot and gave him his first taste of motorcycle riding with some clutch exercises.

 

[maclariz]

Just wondering. Did you use any coating / epoxy or not? How is the stator holding up after some use? Just about to embark on rewiring my GS400 stator.

 

[Nerobro]

It's still working great. The bike charges like it should. I didn't coat it with epoxy, as epoxy will just insulate the windings. I did however wind them very tightly to minimize any movement.

 

[Guest]

Nice set of photos. This will make the project much more approachable for many.

Three thoughts:

1) The rewind shop that helped me said that baked varnish over the winds stopped vibration-chafe failures on the wire.


2) Over the crimped, not soldered joints, I used fiberglass insulation spaghetti stripped from high-temp wire, available at a hardware store. It gets hot in there!

3) I made a tensioning clamp out of two blocks of oak bolted together. A shallow groove carved in the block made sure the wire didn't chafe on the bolts. This let me put full tension on the wire without cutting a groove in my fingers.

MF

 

[maclariz]

3) I made a tensioning clamp out of two blocks of oak bolted together. A shallow groove carved in the block made sure the wire didn't chafe on the bolts. This let me put full tension on the wire without cutting a groove in my fingers.

Would you mind drawing a quick piccy of what your clamp looks like, or sticking a photo on. Sounds like a good idea for not destroying my fingers. I have a few offcuts of beech around, so that may be similarly hard to the oak you mentioned and useable for the clamp. (Off course, there's lots of bits of pine kicking around, but that's probably too soft).

 

[Matchless]

Using wood is the best idea, use one side of a wooden washing peg. The back square part can square up the windings and push them tightly together, it can also be used to take the slight bow out of the windings so that you do not lose any space there.

 

[maclariz]

What am I doing wrong?????

What am I doing wrong?????

I've tried rewinding my own Stator but things aren't going too well.

The first one failed for understandable reasons when a couple of windings chafed on the rotor, leading to an intermittent ground. But I was very careful with the second rewind and did it very neatly with only 35 turns, as opposed to the original 50 and this clears the rotor without trouble. Resistance according to my multimeter is about 1.2 ohms from any one yellow wire to any other. Resistance to ground is > 2 M ohms. Resistance from a yellow wire to the union of the three wires at the opposite end of the stator windings is about 1.0 ohms. Resistance with just touching probes together is about 0.7 ohms. The multimeter looks to be exactly the same as that used by Nerobro with a different colour scheme but all the same switch positions and ranges.

I would therefore correct the real resistances to the following:

Yellow wire to yellow wire: 0.5 Ohm
Yellow wire to union at end of stator 0.3 Ohm
Yellow wire to solder joint at start of stator ~ 0.1 Ohm

Basically this all seems to make sense. The total resistance seems a little low but the magnet wire is a heavier gauge than that used in the original (I used the following).

The output in AC volts from one yellow terminal to another is about 1 V at 4000 rpm and changes a little with RPM. But this is never going to charge my battery. What could I be doing wrong?

Could the insulation of the magnet wire be failing and allowing each coil to short out? Could I have damaged the insulation in winding?

Could something else be wrong that I haven't thought of?

BTW: I have checked the rotor. This seems to show alternating north and south poles facing inwards all the way round the rotor. Also, when I put the LHS cover on with the stator attached, it is pulled in strongly by the magnetic attraction. So, I don't think there's anything wrong with the rotor.

Thanks

Ian

 

[BassCliff]

I've tried rewinding my own Stator but things aren't going too well.

Resistance to ground is > 2 M ohms.

Mr. maclariz,

Are you saying that the resistance to ground is less than 2 Megaohms? If I understand correctly, there should be no continuity at all between any stator winding and ground, no connection whatsoever, absolute infinite resistance.

Thank you for your indulgence,

BassCliff

P.S. I'm glad this thread got bumped. This is a great write-up. Thanks Mr. Nerobro!

 

[maclariz]

Mr. maclariz,

Are you saying that the resistance to ground is less than 2 Megaohms? If I understand correctly, there should be no continuity at all between any stator winding and ground, no connection whatsoever, absolute infinite resistance.

What I said was greater than two megohms, i.e. no detectable continuity (as it should be).

 

[BassCliff]

No math before coffee!

No math before coffee!

What I said was greater than two megohms, i.e. no detectable continuity (as it should be).

Oops, got my symbols turned around. Sorry about that.

Don't the continuity readings between your stator legs seem a little low?



Thank you for your indulgence,

BassCliff

 

[maclariz]

Oops, got my symbols turned around. Sorry about that.

Don't the continuity readings between your stator legs seem a little low?

Yes, was wondering 'bout that.

But the resistance of the whole coil of spare wire is about 1.8 ohms, once the 0.7 ohm offset on the meter is subtracted. So the wire resistance is intrinsically rather low.

 

[Suzuki_Don]

Great article Nerobro. I would be prepared to attempt a rewind myself and as I have a spare in the shed I can do it and measure it for ohms as per the Stator Papers and have a good spare ready to go on the 550 when the other one plays up.

 

[maclariz]

BTW: I have checked the rotor. This seems to show alternating north and south poles facing inwards all the way round the rotor. Also, when I put the LHS cover on with the stator attached, it is pulled in strongly by the magnetic attraction. So, I don't think there's anything wrong with the rotor.

Now three phase AC was never on the syllabus where I studied, and I've struggled to find any really good primers on motorcycle generator/alternator systems on the internet. The best I could find last night was a wind power site using a similar idea of a permanent magnet rotor and a wound stator. Now their example uses six wound poles and four magnet poles. And it seems to me that working things out on a bit of paper, that the rotor needs a different number of magnet poles to the number of wound poles on the stator. I think from my calculations that 18 magnet poles and 12 wound poles (4 per phase) would work, as would 12 magnet poles and 18 wound poles (6 per phase). But I reckon that if you have the same number of magnet poles as wound poles, then all the phases end up in phase, and you lose the potential difference between at least two of the exit wires, and depending which way you connect the exit wiring, between all three wires. Now the point, my stator has 12 poles, my rotor also has 12 magnet poles. This sounds like a disaster. Could mean that although my winding is okay, the stator and rotor just do not match. In this case, my small exit voltages mean I have the odd pole here or there where I miscounted the number of windings....

I heard that there were two OEM suppliers of stators and rotors to Suzuki, Nippon Denso and Kokusan, with different numbers of poles on the stator (12 and 18, respectively). Certainly, mine has 12, but some stators I see on ebay or from various aftermarket producters for the GS400 have 18 poles. I am wondering if combining my 12 pole rotor with an 18 pole stator would work better?

Anyone know anything about this from proper education, rather than just my scribblings on bits of paper?

 

[Nerobro]

The nubmer of poles really would just affect the frequency of the a/c. So don't worry about that. You also can't just swap from an 18 to a 12 pole stator wtih teh same rotor. If the rotor has the wrong pole spacing you could just cancel any current.

I was quite worried with my stator that my resistance was to low. Resistance is really tied to the length of the copper used in the stator. The more copper, the more power you'll get from it. 35 turns versus 50 turns is a rather large difference. You may not have enough turns on the stator to make any real power. Also ALL the poles should be wound the same direction. To get the a/c they alternate the poles of the magnets in the rotor.

I'm going to have to say that either there isn't enough turns of copper involved, or you're still shorting to the chassis. With the motor running, have you checked to see if you get voltage between a yellow wire and the chassis?