Engine only runs with kill switch depressed

Discussion in 'General Questions' started by TWalker, Aug 28, 2008.

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  1. TWalker

    TWalker Guest

    Ok, I have a friend with an HT and it dies if you release the kill switch. He replaced the the throttle/kill switch combo and it doesn't help.

    What would cause this? Where should I start?

  2. s_beaudry

    s_beaudry Member

    Sounds like it may be wired incorrectly....

    How do you have the two wires from the kill switch hooked up? Where do they go?
  3. TWalker

    TWalker Guest

    Its run for months, no wires were changed.
  4. s_beaudry

    s_beaudry Member

    Could very well be a short in the wiring maybe? Are all the connections tight and the wires not frayed?

    The replacement kill switch could very well be bad also, is there a way you can test it on your MB maybe?
  5. Accender

    Accender Member

    Is the engine mounted with rubber (insulated from the frame?)

  6. Mountainman

    Mountainman Active Member

    Hi TWalker - I have read this thread a couple of times now - find it rather interesting. I noticed that you said that it worked for a time.
    I don't know a lot in regards to HT setups -
    I would think - one wire going to kill switch ?

    have you taken kill switch out of picture yet ?
    sounds like time to start eliminating things

    Happy Riding from - Mountainman
  7. duivendyk

    duivendyk Guest

    It is quite possible that the portion of the generator coil between the white wire and the the black wire (Ground) has failed and is now an open circuit.If this is the case and you have the kill switch on the white wire,closing it would provide the needed continuity to ground which is necessary for the blue wire to provide the output to the CDI unit.If this is indeed the case the output will be somewhat reduced but may well be adequate still to generate the spark,provided of course that the switch is closed
    The kill switch ought to hooked up be between the blue wire and the black wire,or alternatively between the blue wire and the input to the CDI unit.In the first case the input to the CDI is shorted,in the second the input is opened.The latter is essentially the same thing as you have presently except that your kill switch is located in the ground return and works in reverse, it is now an "operate" switch in what used to be the "kill" position.
    If you have an ohm meter you can check it by measuring the resistance between the blue and black wires at the engine with
    EVERYTHING disconnected.I should be a few hundred ohms,an open circuit means that my assumption was correct and a portion of the genrator coil has opend up.
    Last edited by a moderator: Aug 29, 2008
  8. TWalker

    TWalker Guest

    After narrowing it down it finally turned out it was the magneto inside the engine case.

    We replaced everything else and when we finally did that it worked like a charm. So the generator/magneto coil was the likely culprit.

    Amazing, never saw that before, but now we know. Hopefully the next guy will find this thread.
  9. duivendyk

    duivendyk Guest

    At least you found the problem but watch out!!,it is possible to have a short from the white wire to ground (the black wire) without the engine quitting on you,but when that happens you may fry that portion of the generator winding,resulting in an open circuit.This is prob. what happened to you!!.Watch out, tape off the white wire,but if you decide to use it for lights etc, put an 1 Amp fuse in the lead from the white wire,it could save you a lot of grief.
    Last edited by a moderator: Aug 29, 2008