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  1. #1

    1987 JS300 IGNITION/Check

    Hey everybody, looking for some conversation and answers about the ignition system on the Kawi JS 300. I personally own a 1987 JS 300. Now I have an extremely weak spark. Not enough to get the engine to fire. I tested my stator and that tested to what I believe is to be normal and acceptable. If someone could please tell me exactly how they would test their stator I would like to double check my work. So the working stator leads me to believe, obviously, that I have a bad coil. So I tested my coil. and I have no continuity. So that would tell me that my coil is bad. Am I correct in saying that? So I ordered a new coil and it will be here in a few days. My main concern and question though is what does the "Ignition Control Box"(that's what the parts schematic calls it) do? What is its purpose? Could that be my problem? How would I test it. I hope for good answers and will be watching for reply's.
    Thanks,
    Anthony


  2. #2
    steve45's Avatar
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    No continuity on the secondary, to the spark plug terminal? It's not unusual at all for the metal core of the wire to break from vibration. You might trim the end of the wire down 1/2" or so, if there is enough wire left, then check continuity.

    You may have to replace the wire, but than you'll have a spare coil.

  3. #3
    It is not the wire. I made a brand new wire. I ordered a coil and an "Ignition control box". I will try that when they come. Ive seen a coil cause weak spark before so I am hoping that's the problem. I hate to blindly throw parts at something but I got a good deal on so ill have an extra set anyway if there good. Can someone describe what the "Ignition Control Box" Does? I would also appreciate if someone could give me some specs in regard to testing all the electronics once again. Now I have new information. I pulled my mag Cover off and found it to be full of oil from a bad seal on the injection pump. I am going to run pre mix anyway. So I pulled the fly wheel and cleaned all the oil off and cleaned the magnets in the fly wheel. This made no difference. I also tried running a separate ground wire from the engine block to the coil, assuming maybe there was a bad ground. This also made no difference. Any ideas are welcome. I am currently in the process of checking any and all wire for breaks or cuts.

    Thanks,
    Anthony

  4. #4
    steve45's Avatar
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    Does this engine have one of those plastic screws on the front cover? The parts book actually calls it an oil filler cap--but it's not. It's amazing how many people actually try to fill that area with oil.

  5. #5
    No. It has the STARTER gear oil in the back. There was oil in by the STATOR because the oil pump has a seal that leaked. I just removed the oil pump. Thanks for your help by the way. I have a wiring diagram now and a test base sheet. Would you be concerned if your stator tested 4 ohms less than the recommended range? I checked all my wiring I am very convinced that it is the coil. Any other ideas? How would you go about testing the other half of the stator. The charging part for the battery and such. they are the 2 green wires.

    Thanks,
    Anthony

  6. #6
    steve45's Avatar
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    Starter gear oil? Never heard of that, but I've never actually seen a one cylinder JetSki engine. I was just looking at the parts manual. The 750s have a plastic plug that looks like a filler plug that people actually try to fill.

    I haven't seen a Mikuni oil pump leak, but that doesn't mean it couldn't--especially after 27 years.

    4 ohm variation out of how many ohms? 10-20% tolerance is pretty standard for electrical components.

  7. #7
    service manual calls for 168-252 ohms. I am reading 164. I suppose it should be good but I am not an electrical expert. I just know enough to get by. Now again my problem is a weak spark. So could this low reading be the problem? I don't think so. The leak was defiantly from the pump. It's clean 2 stroke oil. No gas in it so its not from crank case seal. The backside of the pump seal is wet with oil as well and gets worse even when spun by hand. Anyway that doesn't matter because its converted to premix now anyway. Now service manual also says I should get 5000-7500 ohms out of the coil. I don't get any readings out of the coil no matter how I test it. So I guess im either testing wrong or my coil is bad. I still have no idea what the "Ignition Control Box" Does.

    Thanks,
    Anthony

  8. #8
    steve45's Avatar
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    Sounds like the coil.

  9. #9
    Yea that's what im thinking. Like I said I ordered one and I am really hoping its the correct part. I am anxious to get on the water with this ski.
    Thanks,
    Anthony

  10. #10
    So I put a new coil and "Ignition control box" in and still weak spark. But my Stator seems to be testing good. Any ideas

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