Stator Rewinding Questions, maybe a New Service I'll Offer.

[Maico]

I've got a couple of '86-'87 Tecate stators that you can have if you want to practice.

[ps2fixer]

Yea that would be awesome, not sure if there's a demand for Kawi stators, but I know the flywheels need rebuilding so I'd assume the stators can get damaged too when the magnets fall out of the flywheel (or whatever exactly happens with them). I'll shoot you a PM.

[ps2fixer]

Here's an interesting post of some stator rewind failures. Ironically, the poster didn't have any issues with the OEM units, seems like it would make more sense to run the OEM one instead of buying aftermarket due to the issues he's had.

http://www.genebitsystems.com/david/...torfailure.htm

I'm just reading about some DIY rewinds and such and what kind of failures they had to figure out the correct way to do it. Clearly copying OEM as close as possible seems to be ideal.

I think I've also picked out the grade of stator wire to use, just have to figure out what sizes to stock. 200C rated wire should be more than enough, the lead wire I've been looking at is rated between 150C-200C.

Sounds like the DIY people use epoxy like 3M makes, but OEM manufactures use a style of epoxy that cures with heat in an oven. I can buy/setup an outdoor oven for this, so if anyone knows the proper coating/sealing epoxy used for stators, it would be helpful for me. I also have to buy the fiber braid tubing too, doesn't seem like much is used, but I'm sure it's a very handy thing to have around to insulate between the coil wire and lead wire.

I'm also thinking on how to build/design a mold for the rubber grommets that I'll need. I'm kind of thinking of making them in 3D CAD and getting a hard plastic "master" made that I can sand and shape as needed to build the mold out of. Since I use tubing for my harnesses, maybe I can design it with that in mind to help seal the tubing to the grommet, but then again it would hold water if it was taken in deep mud/water. The grommet I envision will have small holes, one per wire to run though so it should be sealed quite well. Some of the OEM grommets are just a large hole with the group of wires though it with a "tail" of sorts to help keep stuff from getting in it, and probably provide strain relief.

Based on the link above, I'm almost thinking I should buy the related machine's stator cover too or case half which ever side the stator bolts to, so I can be sure none of the wire interfears with the mounting. I'd be hand winding it all, so I can control the wire pretty well point to point.

Here's another interesting read if you have an interest in this stuff. Basically details # of winds vs wire size, and wind patterns (single vs 3 phase, and delta vs Y). Knowing what I know about the 350x and the size of the regulator and such, I'm starting to think the 200w rating on it is way too high for what real world numbers would be. It's a single phase stator, wound with less wire than a 250es/sx that is 3 phase and has a regulator physically like 3 times larger. Based on the link, I should be able to take a short circuit amp reading and get an idea of peak output. Too bad it seems like the spreadsheet for that post is missing now, I see a bunch of html like tags in the post that are not processed right anymore .

https://advrider.com/f/threads/stato...tified.189734/

Anyway, I'm sure it will be pretty slow progress for me to build 100% new stators, but rewinding existing stators I think I'm getting pretty close. Based on what I'm seeing costs wise, something like 90-95% of rewind costs are labor. Makes sense though, rewinding takes a lot of time, or if it's machine wound, that machine isn't cheap.

[RubberSalt]

There is a whole lot you need to take note of before starting this. On my endeavor of rewinding the Tecate stator.... A lot was learned. ChrisP broke his kick start lever and I walk with a limp.

Polarity is going to be the biggest factor out there. If it is wrong you can break engines or yourself. You need a way to check polarity before and after. Before you tear down a stator you need to document the polarity. After you build one you need to confirm polarity is correct. This can be done with a battery and a compass. You left hand and right hand coil rules will tell you how a coil is wound. News rules are associated with North and South magnetic poles.

All your pickup in trigger coils need to stay within oem spec. If you get two many windings the voltage raises too quickly and will cause the timing to be off.

There's a whole bunch of information I'm willing to share. There's even an write-up on the Tecate 3 stay here I did that covers a bunch of this and how to. There is also a specific electrical epoxy that can be used. Anything you use to coat wire needs to not cause a reaction over time. Electrical epoxy it's fairly inert. Before you epoxy you need to clean with alcohol.

You want to use 200c magnet wire, vintageconnections.com can provide connectors. Marine-grade wire is it going to be some of the best you can use. Almost all magnet wire is oil proof. Magnet wire itself is enamel coated.

[ps2fixer]

Yea, I have a potential source for enamel coated wire, 200C rated, but having other locations is good too. Connectors I order from cycleterminal.com, and when I can find the right part numbers I buy in bulk from mouser.com and other electrical supply sites. Buying Japanese branded terminals is a must, the Chinese ones are so thin and crimp like crap.

For the lead wire, I'm looking at using silicone insulated wire that has a fiberglass braid covering. It says high resistance to oil and if I remember right it's 200C rated. The "normal" wire I use is 125C rated GXL grade which uses Cross-linked Polyethylene (XLPE) insulation. Do you happen to have the specs for the marine wire? I don't see why marine wire would be high temp spec'ed though.

Polarity shouldn't be hard to figure out, the coating might be hard to see, but I'm sure figuring out which direction it's wound can't be that hard. Single phase it switches polarity every point from my understanding, 3 phase it stays the same direction but skips 2 points so every 3rd is the same coil. I didn't look to deep into the delta vs Y wiring, pretty sure it's just how the coils are hooked up though, I think the winding process is the same. Since it's AC, I wouldn't think it would make a huge difference if the whole thing was wired backwards, given the polarity pattern matches the stock config. The exciter is probably a different story though, since I'd assume the CDI uses the first peak of the wave to charge the capacitor. Having that coil wound for higher voltage should in theory give a hotter spark as long as it doesn't go above what the CDI can handle. Voltage isn't everything though.

For the heavier gauge wire (lighting coils), I suspect I can probably get an accurate wrap count to keep with OEM spec. The exciter coil on the other hand is a bit harder to measure. I'm not sure of a reliable way to keep the hair sized wire the right length besides just doing it and checking the ohms. I kind of have an idea on how to measure the length with a roller style distance measuring tool (not sure what they are called). Probably have to be a bit of trial and error, but the new wire should also give a ohms per foot spec to base the length needed on.

This reminds me, I have an 79-81 style ATC110 stator I got that's from an unknown machine. Same size physically as the 79 ATC110 stator I have, but manufactured slightly different. Guessing it's probably from a US90/ATC90, or a different year ATC110. I guess I'll make it my first target, since the wires are already pretty trashed and I see some small physical damage to the coils where the epoxy was knocked off.

[ps2fixer]

Well I started the impossible. Ohm tested the stator, and besides bad lead wires, the exciter (black wire) tested open circuit so starting with a junk stator anyway. Lighting coil tests as 0.4 ohms, same as my good atc110 stator. The epoxy Honda uses is some pretty strong stuff, but it seems every epoxy's weakness is heat. I work with soldering and such, so I have a solder rework station with a temp controlled hot air gun. Setting to about 250C seems to work well for the epoxy to get soft enough to pull the wire up. Pretty interesting only the outer layer had the epoxy on it, I thought the OEM stuff penetrated more. Anyway, lighting coil I counted 66 wraps twice (2 points used for lighting coil). Since I got the same number twice, I think I counted it right. One was clock wise and the other counter clockwise as I was guessing (I have notes which way each one was).

The exciter coil wire is a tiny bit smaller, but not much from the lighting coil in this stator. I got the first coil unwound using my hot air trick and counted 129 wraps (might have been 130 and I mis counted, not 100% sure). However, it seems I found where the wire is bad, going to the next coil it's broken off right at the next point. I get to fight that next to get it started again so I can count the wraps on at least one more point so I'm sure I'm accurate. Exciter coil is 4 points of the stator, so if the 130 number is correct, that's 520 wraps. So far it's kind of fun learning how these things are put together. Cleaning up a used stator core looks like it will be a pain though. Maybe the trick is once the wire is off, bake it in the oven at a high temp setting to burn the epoxy a little so it can flake off? Advice on that would be helpful. I'm not aware of anything that dissolves epoxy or makes it more elastic/soft for removal besides heat.

Since I have the wire sizes measured, I Probably should order the wire too. Lighting coil should be 18 gauge, and exciter 20 gauge based on my measurements (nearest gauge vs diameter measured).

Anyway, some photos for fun. Ignore the mess.

Also, if someone needs this style of stator, I don't have a machine that runs that can take it for testing, so if you don't mind the testing and possible failure (I'll rewind if it fails free) then I could sell this one for a reasonable "rebuilt" price. Shoot me a pm and we can figure out what reasonable actually is lol.

EDIT: Yep I miscounted the first time like I was thinking, 130 wraps for the next exciter coil point, so 520 total wraps for exciter, and 132 for lighting coil. The stator metal core is bare now =).

[RubberSalt]

Each stator is different, thats for sure. It's definitely good to document with photos and what not. Thats cool your able to pull it apart more gracefully. The tiny source coils used on Tecates, Tri motors, etc... Are 34-36 guage. talk about small.

As for baking, I'd be against it. The iron laminates for the stator have tiny dividers (plastic, lacquer, etc). The need to remain electrically isolated. The flat electrical steel is designed to control eddy currents. I've never been able to source electrical steel sheet or plates. A material that has a higher magnetic permeability will generate more power in the windings. There are a few things out there better than the electrical steel used in stator plates. Getting a hold of them is a pain. Think of it as a magnet sticking to sheet metal vs a block of iron.

This chart sheds light on the permeability of materials. 99.8% pure iron is 25% better. 99.95% pure iron annealed in hydrogen is 4000% better.
https://en.wikipedia.org/wiki/Permea...ctromagnetism)

[ps2fixer]

Yea, this is from a points engine, so probably a pretty big difference there for the exciter coil. I've worked with 30 gauge wire before, fairly strong stuff but I'm not sure if it would hold up even to the heat trick or not. Counting like 500 wraps all in one go would be a pain lol.

So the stator iron cores are not just basic steel? I figured I could CAD up the design and weld up my own with the top/bottom plates having an overlap that I bend at a 90 degree angle as a keeper. Reading a bit more from that wiki and related pages seems to really suggest standard steel would work, but create a lot of heat and be inefficient . Thanks for the heads up on that one.

What's the typical cleanup job for rewinding stators? I kind of want to remove all the old epoxy so I can coat it with all new. Degreasing it and such shouldn't be too hard, I can setup a tub to bath it and scrub if needed.

I found this company that specializes in prototypeing stators (low to med production volume). I'll have to come up with a CAD drawing of the stator and see how much they'd charge for a low production run of it. Based on the place that linked to the site, it said a single one can cost $100s, but it didn't say anything about higher quantities. Maybe 100 qty would drop the price to like $10-30 each core (wishful thinking right? lol)

http://www.protolam.com/

Defo interesting read, not sure if I'll be able to make 100% new stators or not now. Rewinding doesn't seem that bad though, just have to pay attention to details.

[christph]

Yea that would be awesome, not sure if there's a demand for Kawi stators, but I know the flywheels need rebuilding so I'd assume the stators can get damaged too when the magnets fall out of the flywheel (or whatever exactly happens with them). I'll shoot you a PM.

Actually, Tecate stators burn out all the time. If a Tecate isn't running that's often the reason. Mine burnt out so often--usually at maximum distance from my truck--that I started rewinding them myself. Since then I haven't had a problem. I used 34 gauge wire because I wanted to wind more loops and there's not much space. In fact, I couldn't get the number of loops I wanted even using 33 gauge. You're also correct about the flywheels. 30 year old glue tends to give away at 9000 rpm.

[ps2fixer]

Yea, I heard about the flywheel problems before, I had a "core buying list" type of post ages back, but it seems no one ever used it, at least I didn't have anyone contact me about cores.

Do you know the stock wind count for the tecates? I'm assuming taking the ohm reading and stock gauge size wire ohms per 1000ft spec would give you a good idea for total feet wound. I'm just wondering how much more winds you got with the smaller gauge wire (estimates).

Either case it seems like pretty easy work, I just don't think I can make rewound stators look like new too easily besides the fresh epoxy and new lead wires. I know appearance sells for the general population.

Have any photos of your rewound stators? A before and after photo would be awesome just to compare other's work with my own. I have very little reference to measure my "performance" against besides companies that do this type of work in bulk and has machines to do half or more of the work for them.


I've seen Essex branded coil wire seems to be commonly used for rewinding stators, I saw one site that does this service mention they use their brand as well. Not sure which spec to get though, a couple seem to meet the stator application needs. This one seems to be more overkill for specs, maybe the best suitable wire?

https://essexwire.com/sites/essexwir...e-imide-en.pdf

This seems more of the typical used stuff

https://essexwire.com/sites/essexwir...ld-Plus-EN.pdf

Here's lower temp stuff, 155C seems to be on the low end of what can be used though.

https://essexwire.com/sites/essexwir...-FS-155-EN.pdf

The site that mentioned they use their wire mentioned it's enamel is double coated (heavy) and rated 200C, but I don't see anything with that same spec on their site.

Did some shopping around, ironically, best deal I can find for small qty (1-5lbs) is on ebay. I have 5lbs coming, 1lb of 20 gauge, and 4lb of 18 gauge. Getting closer to having everything I need =).

[christph]

Usually service manuals will list the acceptable ohm range for a good source coil, and I wind it towards the higher number. I wind my Tecate coils to 220 to 230 ohms, which is about 1000ft for 34 gauge wire. I wind by hand because it gives you more control and tighter coils. My technique is to measure out 10 ft., pulling the wire off the spoil, wind it back to the spool, repeat. I thread the wire through a stiff straw (actually the core of an ink pen) to wind; it's much faster than just using your fingers and offers more control. I also put a little weight (another straw) on the wire to keep tension on it. 10 ft. of thin gauge wire will turn into a knotted ball if you don't keep tension on it. I use the wire rated at 200C. Tecate coils get very hot and the epoxy breaking down is one of the reasons they fail. I provided a link to the company I get my wire from. They have a wide selection and fast shipping. For protecting the coil, I use red insulating varnish from MG chemicals. Since I put more loops in the coil, I had to wind it to an hourglass shape so it won't rub on the crank. Here are some pictures.



https://www.remingtonindustries.com/

[ps2fixer]

Based on the page I found for the insulating varnish, it's rated for 180C, pretty much the heat range I've been targeting (200C+ ideally).

Ohm spec is probably a bit of a catch 22. Say the OEM wire is smaller, the ohms per foot is higher, so realistically if you use larger wire the ohm spec would be a little lower for the same distance. Winding 1000ft of that tiny wire is pretty impressive, must have taken what 2-3 hours to wind? I suspect a drill setup could be faster, but like you said, harder to control. The pen core and tension ideas sound like good ideas to me. I've done kind of similar respooling 1000ft wire spools (well the spool can hold something like 5-10k feet), and put it on 250ft spools to be easier to handle. It's really hard to make it even though, but I was using a spool holder I made and a drill.

Either case, looks like your work came out quite clean looking. Did you do much to prep the core, sand blasting or anything like that?

[christph]

The core is from burnt out stators. Cutting away the old epoxied wire is a real pain, especially without damaging the core. I use a Dremel tool with a diamond cutting wheel. After that, I wrap the core with cloth electrical tape so the hard edges don't wear through the wire and short it out. At the ends, I use thin strips of copper about 4mm wide (cut from a sheet) for connecting the magnet wire with the leads. That gives a more sturdy connection between gauges that are so different in size. Yes, it takes a long time to wind. Since I'm only doing my own it's not too bad. If I was offering it as a service I would definitely consider a more automated technique.

[ps2fixer]

I've seen the small wire gauge be wrapped around the larger size, then soldered pretty often. Sounds like copper tabs would work well too, but I'd think it would be a bit of a fight trying to solder 3 things together instead of 2, maybe it gives better strain relief though.

The Honda core I pulled apart has some sort of thick coating that was between the coil and the metal core. I see no damage to it, so in this case I'm thinking about leaving it alone. The other stator I have on hand that's from 79 ATC110 had junk lead wires, super stiff and dry rotted. After I rewind this unknown stator to it's orig spec as it came off, I'll have to decide if I want to rewrap this second one, or just replace the lead wires on it. It tests good on both wires.

Also the grommet that came from this first one is in pretty good shape, just stiff, once I build up more funds I'll have to give making a new grommet a shot since it's nice and small and pretty simple shape. Wish I could just find a place that sells grommets that are already the right shape and such for my needs lol.

[christph]

Using thin copper sheet also allows you to keep the stator thin and provide a solid mount for the leads. I bend them like an "L" so they stick out the ends (see picture), and that way they provide a solid mount for the leads. I wind the magnet wire around them to keep them secure.