2000 KTM 640 No Spark

Discussion in 'Thumpers' started by maverick42190, Oct 7, 2012.

  1. maverick42190

    maverick42190 n00b

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    I have researched this topic and I am at a dead end. I was having starting troubles. I ended up replacing the intermediate starter gears (three missing teeth) and the stator (the teeth got into the flywheel and tore up the old stator). Now I have no spark and the bike won't start. The new stator seems like it is good so I went to the pulsar coil. I tested the resistance and got 98 ohms (right in range), so then I tested it with an o-scope and got about 20mV at most. Why am I getting good resistance and no output? I believe I need a new pulsar coil but I am confused about the resistance reading. Thanks for the help.
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  2. Luke

    Luke GPoET&P

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    The resistance means the windings in the coil are probably good.

    Did the pulser coil or the tooth on the flywheel get damaged when the junk was flying around in there? What's the gap between the pulser and the tooth?

    The peak voltage from the coil should be 4 to 5 V from the pulser with the CDI unplugged. You'll probably need a storage scope (digital or analog) to catch it.
    #2
  3. maverick42190

    maverick42190 n00b

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    The tooth looks ok (the one that is attached to the outside of the flywheel) and the gap is 0.030" (what is called for in the service manual). The oscilloscope we were using showed the peak on a chart that was saved for several seconds so we should have seen a larger spike I would think. The coil does have a few scratches on it.
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  4. maverick42190

    maverick42190 n00b

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    I also tested the starter coil (it checked out fine), ground to starter coil, ground to cdi, coil to cdi all checked out fine. The engine cranks fine and the supply like to the capacitor has full voltage so I don't think it's a safety switch somewhere. Didn't do a check on the stator but it is brand new.
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  5. maverick42190

    maverick42190 n00b

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  6. Luke

    Luke GPoET&P

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    It looks a little scratched, but I'd think that wouldn't matter. :dunno OTOH, if there's no output and the flywheel tooth is good then it must be broken.

    By the way, the orange wire going to the CDI is its power. If there's +12V on it then you know that all the ignition and safety switches are all working.
    #6