Stators demystified

Discussion in 'Thumpers' started by Luke, Dec 17, 2006.

  1. StevenD

    StevenD Hmmmm, dirt!

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    A r/r can't 'up' the voltage, so something strange going on there with your meter perhaps? Why if your going with a single phase winding, still go with 3 r/r's? Why not just take one that has the capacity for your amp's output?
  2. rIZOOgs

    rIZOOgs Adventurer

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    Agree, I think it's the effect of capacitors (13.6mF). The original R/R which is used only to topup the battery, refuse to make juice

    Still believe in my Japanese meter though :webers

    Basically I want to make 3 phase coil, but what to do if can't find the 3 phase R/R? So I ordered 2 single phase R/R

    I will rewire all & hopefully will try with dual R/R, instead of 3, due to the availability of components to support double R/R
  3. rIZOOgs

    rIZOOgs Adventurer

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    I forget that I have recorded the OCV before hooking up the RR. It's fluctuating from about 39VAC on low rev to about 19VAC on high rev.

    Screenshot_2019-09-09-21-25-43-985.jpeg

    Screenshot_2019-09-09-21-24-24-913.jpeg

    You can see how it moved here:
  4. JensEskildsen

    JensEskildsen Long timer

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    Hi, Im chasing some rough running/idling and hard starting on my xt550. It kinda skips a beat every 2-3 secs at idle, and can be a bitch to restart when warm.
    Valves are within spec, plenty of compression, and decom-cable adjusted to 1mm slack

    Its kinda been this way since I purchased it, but I just found some fresh energy to get it sorted.
    I've ohmed out all the connectors from the stator, and they all check out fine according to specs in the manual
    I've also submerged the stator in petroleum and meassure again to try and rule out shortings.

    The stator has a few weird things going on, the epoxy looks kinda sketchy in a few places, but dont know if its always been like that.
    Theres a few places with small holes, but the wires could still be well sealed underneath.
    Theres a pole/winding thats a bit darker and is slightly black, but I've seen that before on other working stators. It doesnt look burned out.

    I've also tested meassured ohm right after a trip, on a warm bike, they were still within specs.

    Any inputs?

    [​IMG]
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  5. magwych

    magwych Been here awhile

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    That sounds more like your ignition coil breaking down.
  6. JensEskildsen

    JensEskildsen Long timer

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    Ignition coil is brand new and meassures in spec both cold and warm
  7. XRHondafan

    XRHondafan Long timer

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    Solid blue spark from plug against the barrel ?
  8. JensEskildsen

    JensEskildsen Long timer

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    Yup, spark is fine. Every normal scenario shows the stator to be fine. Specs are perfect hot and cold.
    The epoxy looks brownish, where others I've seen show up clear, so it might have been rewound at some point.
    I borrowed a stock stator from a friend, bike started on 2nd kick, and when warm could idle below 1000rpm with no "misfires"
  9. XRHondafan

    XRHondafan Long timer

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    You’ve done the right thing swapping in a known good stator.

    There really seems to be a big difference between oem stators and aftermarket
  10. Doug_M

    Doug_M '09_K1300GT '06_R1200GS '08_KTM450XCW

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    Winding direction and unused poles? (Apologies if this has been answered earlier in the thread and I missed it. )

    I want to increase the current output from a TTR230. The stock stator has windings on the poles at 12 o'clock, 9, 6, and 3 o'clock. There is a set of another set of unused four poles in between these. My thinking is to rewind with half the number of turns on each pole, and to use all eight. If I recall correctly, the stock windings all wrap in the same direction.
    Am I right in thinking that the in-between poles should be wound in the opposite direction? (I guess I don't have a clear understanding of how the rotating permanent magnet is configured).

    Cheers,
    Doug
  11. Luke

    Luke GPoET&P

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    Yes, pretty sure you've got that exactly right.

    You can figure out the pole configuration by counting the magnets in the stator. If they're covered, use a piece of steel and see how many places it sticks.
  12. Doug_M

    Doug_M '09_K1300GT '06_R1200GS '08_KTM450XCW

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    There are magnets in the stator? Now I'm really confused. I thought the permanent magnets were in the flywheel (rotor) and the stator contained a laminated iron/steel core to help steer the magnetic flux through the wire coils wound on the "poles" of the stator. It's the change in flux through the wound coil that induces the voltage, right?
    How the North and South poles of the permanent magnet(s) in the rotor and arranged would, I think, affect how the windings need to go. At least that's what I've been thinking.
    Because the stock stator (IIRC) has them wound in the same direction, I had assumed that the permanent magnets were configured something like this: Imagine a North pole on the rotor beside each iron pole on the stator that has windings, and a South pole beside each pole on the stator with no windings. The field lines are steered from N to S through the iron and through the coils. As the rotor rotates we get to the point where we have S at each pole with windings. The change in flux over time happens the same way for all the coils, so they should be wound in the same direction. But, if we wind the in-between iron poles, they are having the flux change in the opposite sense, so for the induced voltages to sum, not cancel, their winding direction must be opposite.

    Make sense?
    Doug
  13. fadingfastsd

    fadingfastsd Been here awhile

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    Doug, you are correct, I think the post you were replying to was just a typo. There are no magnets in the stator, they are all in the flywheel, and it works as you described. On the original stator, the coils are all wound the same way, but this because they skip a pole in between, so this makes the coils lines up correctly with the magnets. If you are going to wind every single pole including the empty ones, you will need to alternate winding direction Clockwise / Counter-Clockwise on each adjacent pole. If you wound them all the same direction, you would have very little current flowing as they would be canceled out. Hope this helps!
  14. Luke

    Luke GPoET&P

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    Yep. Magnets are on the flywheel.
    Brain fart . Sorry.
  15. dentvet

    dentvet Long timer

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    speaking of flywheels, i have a mild conundrum. I chased a no spark condition on a basketcase Husky for the past week. Two stators both ohm normally, two ignition coils ohm normal. All wiring double checked, wiring schematic memorized. Everything good except for a pulse from the CDI.

    Ordered a replacement CDI and still got no spark. Problem finally solved when I tried a different flywheel. Husky 250 CDI demands a 250 flywheel. I was trying to use a 450 flywheel. Visually, the strip of metal on the flywheel periphery that triggers the trigger coil is longer on the 250 flywheel and has a small second trigger patch adjacent to it.

    The end result is that I have a 250 flywheel and cdi on a 450 motor, which i think will be ok. (250 and 450 stators are identical, which made me assume the flywheels were as well)

    Am I correct in thinking a flywheel is balanced on its own and not as part of an assembled crankshaft?
  16. fadingfastsd

    fadingfastsd Been here awhile

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    I'm no expert on Huskys, but almost for sure you mixed the 250 / 450 CDI and Flywheel. With the different timing triggers on the flywheels, they would never work with a CDI that wasn't expecting that trigger configuration. Or, if they did work to trigger the CDI, the timing could be so far off the motor would never want to run.

    If the taper on the 250 and 450 flywheels are the same and they fit the crankshaft, then you can likely run a matching CDI with it and be fine. This assumes the timing trigger offset from the keyway is the same on them, so they pass the pickup coil in the same orientation (firing at the same time). The timing curve is probably about the same between the 2, so the motor wouldn't care.

    You're correct that the flywheel is balanced totally independently of the crankshaft. It won't cause any balance issues to have changed it.

    Hope that helps!
    dentvet likes this.
  17. dentvet

    dentvet Long timer

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    20200915_165820.jpg circa 2006 had kokusan ignition, similar to ktm. Its possible that the 450 bike didn't have a tachometer, is the small second trigger patch related to that function perhaps?

    Bike is up and running but I didn't actually check the triggers with a protractor, it certainly looked like tdc was at the same place.

    Attached Files:

  18. fadingfastsd

    fadingfastsd Been here awhile

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    Ya, those flywheels would definitely not be interchangeable with the same CDI box. Some CDI systems just use 2 triggers on the flywheel for more RPM calculation accuracy. It is not likely related to a tachometer function.