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Thread: '92 K75 starter relay

  1. #1

    '92 K75 starter relay

    I have a 92 K75 with 30,000 miles. A month ago, I took apart the ignition switch and cleaned it and replaced.

    I replaced the battery with a smaller one (my error) but the bike still started and ran. About 20 miles out, the starter motor started running so I shut the bike off and was able to disconnect the battery before the starter motor burned up. Online, I find out the starter relay welded shut due to low voltage.

    Ordered a new battery and relay and installed. My battery charger was lent out so I just hit the starter button. The bike ran for about 2 minutes, the red battery light came on and . . . the starter motor started spinning. Disconnect battery. It had a 12.6 voltage.

    Ordered 2 relays, and installed one with fully charged battery @ 13.6 volts.

    Hit the starter, bike started and 10 seconds later the red battery light came on but I shut the bike down ASAP. Battery voltage down to 12.6 volts.

    Any ideas?? Alternator?

  2. #2
    Liaison 20774's Avatar
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    Not sure I really understand the concerns for the battery. A reading of 12.6v is not out of the ordinary. A fully charged battery is going to be around 12.7v or so...it can't be 13.6v unless you take a battery measurement immediately after removing the charger. There will be a static charge on it before it drains off relatively quickly.

    Have you read the battery voltage while cranking the engine as well as when the engine is running at say 3000 RPM? That should let you know the health of the battery and charging system.
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  3. #3
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    Your symptoms are not the usual symptoms of a low battery causing the welding of the starter relay contacts. Normally, when relay contacts get stuck, it is DURING the act of starting the bike. If they don't get stuck during starting there is no signal to engage the starter while you are riding.

    The fact that you state that the starter engaged by itself after it had properly disengaged after you started it, leads me to suspect the starter button. Did you also clean it when you cleaned the ignition switch? If so, it probably didn't get reassembled correctly.

    As Kurt previously stated, the 13+ voltage that you noted on your battery is just the result of just taking it off the charger. Normal voltage is around 12.6 - 12.7.



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    Lee Fulton Forum Moderator
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  4. #4
    Registered User kioolt's Avatar
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    On the early k-bikes even if the starter button is pushed while the engine is running the starter relay will not activate because the ECU turns off the ground side of the starter relay. The starter button supplies +12volt. The relay won't work without both. This would hold true even if the button is damaged, stuck or purposely being pressed.
    2004 R1150RT 183,000 miles , 1991 K100LT 128,700 miles, 1982 R100RT 106,900 miles
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  5. #5
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    Quote Originally Posted by kioolt View Post
    On the early k-bikes even if the starter button is pushed while the engine is running the starter relay will not activate because the ECU turns off the ground side of the starter relay. The starter button supplies +12volt. The relay won't work without both. This would hold true even if the button is damaged, stuck or purposely being pressed.
    That is correct!

    And I knew that. It just seems the older I get the more trouble I have remembering all the things I know.. I use the starter button, with the engine running, to give me an idea about the mixture since pressing the starter button also enrichens the mixture.

    Based on that, I don't have any idea how, with a new relay, the starter would start to turn minutes after the starter has disengaged.




    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

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