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Points to GN250 Electronic Ignition Conversion

Discussion in 'The Garage' started by Jim, Aug 15, 2020.

  1. MaxPete

    MaxPete Lucille, Betty & Demi - I suggest but THEY decide. XS650.com Supporter Top Contributor

    You’re a whiz Jim!
     
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  2. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Well this is interesting...
    Here's the sensors I picked up based on @Team Junk 's recommendation. Don't recall what they're for. I'll add that info shortly. These sensors are a magnetic, 400Ω coil. I'm still not completely convinced having a magnetic coil as well as a magnetic target on the rotor is the ideal setup. The one on the left is as made (wires added by me). The one on the right is one where I bent the mounting legs straight, trying to come up with an easy way of mounting it.

    z300.jpg



    Anyway.... I got to fiddling with it and discovered it can be disassembled... and pretty easily I might add. Disassembled it by hand using no tools. As you can see here, the magnet and iron core can be separated from each other.


    z301.jpg


    z302.jpg


    z303.jpg


    So what you see stuck to the magnet on the rotor is a non-magnetic coil.... just like the TCI sensor (which we know works). The TCI coil is 700Ω's and this one is 400Ω, so I'm not sure what kind of power it'll generate. I'll dig out the twirly bits I used before and see what we get.

    As it came, figuring out how to mount it was bein' a bear... couldn't figure an easy way. Now, making a mount for it has become much easier. It's a whole new ballgame now boys and girls. Stay tuned.

    EDIT: Here's the coil. $7.49 on Ebay
     
    Last edited: Nov 14, 2020
  3. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Finally got one of the O-scope apps to work... sorta' :er:

     
  4. MaxPete

    MaxPete Lucille, Betty & Demi - I suggest but THEY decide. XS650.com Supporter Top Contributor

    Hey Jim: That looks pretty promising....I think.

    BUT - I'm not conceding anything!

    .....ooops - no politics...sorry, my bad. ;)

    Pete
     
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  5. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Learned a bit... turned off ch. 2 info. Figured out how to save the trace as an image. It's a start I guess...

    TCI 1550rpm-2.png
     
    Last edited: Nov 15, 2020
  6. Signal

    Signal XS650 Junkie Top Contributor

    Great work Jim, goodness your drill press is quiet.
     
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  7. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    I've got some baseline values to work with now. Not really sure what to make of 'em :umm:... but all I need 'em for is to compare them to the sensors I try going forward. These are based on the stock TCI pick-up and magnet... which are proven to work with the GN250 box.

    250rpm. Startup speed... or thereabouts.
    025 47mv.png 050 36mv.png 075 28mv.png


    1500rpm. Idle.
    020  221mv.png 050 162mv.png 075 128mv.png


    3100rpm. Full advance (scope amplitude reduced)
    020 376 3100rpm.png 050 265 3100rpm.png 075 191 3100rpm.png
     
    Last edited: Nov 16, 2020
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  8. Jan_P

    Jan_P XS650 Addict

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    Hi perhaps
    I have worked with sheet metal in the past and some on construction sites
    The markup of the holes to drill perhaps could be marked with a Compass ( as to draw a circle )
    Going from the existing mounting holes from the right hole the radius 69 mm
    and then do the same thing from the left mounting hole a measure that you perhaps are kind enough to provide
    Those two arcs will then intersect in a crossing ..the drill point
    Perhaps that will be simpler standing on Your Knees. So to speak under the streetlamp

    Perhaps a paper template that can be printed out in 1:1 scale with the hole points
    Fixating the paper in the mounting holes ..and then markup according to template .

    For example with Punchmarks .. and then drill and thread ... Something then also possible to do under the streetlamp
    If one is careful getting the holes straight

    Thinking out loud would not a slit on the upper mount be an advantage ..giving some room for adjustment.
    I have not read all so Apologize if this is not Possible.
     
  9. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Yes, the top mount hole will be an adjustable slot.
     
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  10. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Tested the Yamaha RXZ magnetic pickup. This little puppy is wild. At 1500rpm and a .025" air gap, this thing cranks out 1.32volts. :yikes:
    Couple other things jumped out at me... for one, it's a lot noisier than the TCI pickup. Also, the top and bottom of the trace is chopped... not sure why?
    Took the air gap all the way to 0.1" and it was still puttin' out close to a volt. I'm thinkin' magnet on magnet isn't the way to go?

    1.37v 1500rpm 025 gap.png 1v 1500rpm075 gap.png 932mv 1.0 gap 1500rpm.png

    magnetic sensor.jpg
     
  11. MaxPete

    MaxPete Lucille, Betty & Demi - I suggest but THEY decide. XS650.com Supporter Top Contributor

    Interesting - an output of 1.3v would be pretty high as a trigger wouldn't it?
     
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  12. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Well Pete, this ain't my specialty... so I'm kinda in uncharted waters here. I think that is too high. I'd guess we need to be more in line with the TCI trigger since we know that works. Tomorrow I'll try the same pickup with the magnet removed and see what we get.
     
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  13. Jan_P

    Jan_P XS650 Addict

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    Not sure I understand it ..but for having the electronic Gonzo box one needs a magnet in the rotor
    ( if I understand it right ) # 26 here
    Inserting one is difficult and risky . Getting the old rotor off .One needs a tool
    And the hole for the magnet must come in the right position in relation to the TDC ..via the Keyway or markings
    That is not a job done under the Streetlamp ..Standing on the Knees .. That everyone can do themselves
    A replacement costs 160 Euro ca $ 190
    I doubt it is cheaper to take it to a mechanical shop here. Let them drill ..
    I have rewound 2 rotors neither costed less than ca $ 100

    https://www.xs650shop.de/en/electric/1099/alternator-rotor-70-84-exchange?number=24-0060

    My Boyer has the pickup and magnets on the camshaft end I believe two of them. Each
    Even though it is perhaps not a perfect solution it does not involve removing or drilling in a expensive Rotor
    that is prone to break when handling it.
    Cost wise if I am not lost here .It appears to reduce the grand total cost if the pickup was on the
    Cam shaft end. On the earlier models that does not have a magnet as it seems.
    Even if it means some more electronics for the signal.

    Again I feel a bit sorry for mentioning this since the job done is important .Those Pick up signals I believe someone needs
    further on.
    I have worked with product development ..generally speaking the sooner the better. If existing not imagined problems
    Are mentioned.
    A solution can be found .Perhaps it is simpler for you in America to do what at this point in time seems expensive here.

    Low Cost. Under $50 is the target. ---- the Rotor job tends to crash that by a factor 2 X
    Am I Wrong ???
     
  14. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Yes, you're wrong. Have a read here Jan. Eventually I'll move some of that info over here. Until then, bear with me... there is a plan.

    zz.jpg
     
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  15. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

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  16. MaxPete

    MaxPete Lucille, Betty & Demi - I suggest but THEY decide. XS650.com Supporter Top Contributor

    ABSOLUTELY - and Jim's rewinds are perfect.
     
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  17. Paul Sutton

    Paul Sutton Still Looking Good Top Contributor

    Just Brain Farting: Perhaps put an approx. 300 Ohm resistor or higher in series with the coil to tone the peak voltage down a little?
     
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  18. xjwmx

    xjwmx It's just the unknown. Top Contributor

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    The clipping on that one wave will probably go away if you set volts per division higher. Or there might be something to set on the display. The high output means you might be able to adjust timing by moving the pickup in and out, since shrinking the wave effectively changes where in the rotation it crosses the voltage threshold to be detected, depends on how pronounced the ramping up is. Magnetic pickup probably means you can use a steel washer attached to the rotor instead of a magnet. If you want to limit a too high output, a voltage divider look up voltage divider formula, will lower the amplitude without affecting the shape.
     
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  19. xjwmx

    xjwmx It's just the unknown. Top Contributor

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    If the output is high enough and the ramp slow enough and my theory about amplitude effect on timing is right, then instead of a voltage divider you could use a trim pot wired like a divider and fine adjust the timing by twisting its knob
     
  20. RustiePyles

    RustiePyles Semper Fortis

    @Jim what is that O-scope program you're using? Where did you get the dongle for the probes? I think I need one of those, sure beats my CRT O-scope.
     
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