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Thread: Coil Sparking on Start

  1. #1
    Registered User Manitou_Commando's Avatar
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    Mar 2008
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    Manitou Springs, CO
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    Coil Sparking on Start

    While putting is a starter on an '88 R100RS, I saw that the coil was throwing off a spark, only while I press the starter button. When it's idling, it doesn't spark. I removed the

    Enduralast twin tower, 0.07Ohm coil from the bike, cleaned it and the three connections to the harness. Running my thumbnail of the surface, I neither saw of felt any cracks.

    Put it back together and it still sparks, but only while the starter button is depressed. No sparking while idling.

    New coil time or not? Thoughts?
    Rick

    "It ain't what you don't know that gets you into trouble. It's what you know for sure that just ain't so." Mark Twain

  2. #2
    Registered User STEVENRANKIN's Avatar
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    Dec 2006
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    Spark plug lead?

    You don't say where the coil is sparking?

    Is it possible your spark plug lead has bit the dust? They don't last forever. A breakdown in insulation will cause the spark to jump to the nearest metal. It could just be a coincidence that it is noticeable when you have the starter button pushed.

    I used to poke around the spark plug wires with an insulated large screwdriver grounded to something, at night to find a bad spark plug lead.

    My sister's Isuzu PUP used to give the best light show! It ate spark plug leads every two years. St.

  3. #3
    Registered User lkchris's Avatar
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    Your coil gets 12V while the starter motor is running.

    After that, it runs on 6V.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

  4. #4
    Registered User STEVENRANKIN's Avatar
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    Snowbum's website

    This fellow, is one of the true experts on BMW motorcycles.

    Perhaps reading some of the information he has posted at https://bmwmotorcycletech.info/ignition.htm

    Could solve the problem. St.

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