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Thread: '87 K75C Battery Change

  1. #1
    Registered User
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    Woodbury, MN
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    '87 K75C Battery Change

    Just attempted to replace the battery in myí87 K75C. When placing the second cable near the battery terminal, I got a unpleasant spark and the starter motor started to run. I imagine I have an electrical problem?

    rickt

  2. #2
    3 Red Bricks
    Join Date
    Jan 2007
    Location
    Pleasanton, Ca.
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    4,806
    Rickt,

    In the future, please include the year (and model) of the bike in question IN THE TITLE of your thread. I will add it for you now, but in the future, please include it.


    What you have is a starter relay that has fused (welded) its internal contacts together due to trying to start the bike with a low battery.

    You will need to remove the fuel tank to access the inside of relay box which is the boxthat has the fuses on the left side of the bike under the battery cover. The starter relay is the one at the right rear. It has two large wires and two small wires on it. You need to remove it. Mark which wire go where.

    If you are VERY lucky, you MIGHT be able to dislodge the contacts by lightly rapping on the side of the relay. Check for continuity between the two large terminals with a multimeter. If it is unstuck, you will get no continuity.

    New relays can be bought (much cheaper than the dealer) at Euromotoelectrcs.

    https://www.euromotoelectrics.com/pr...rel-k008oe.htm








    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  3. #3
    Time flies. Isnít this the same problem you had previously?

    https://forums.bmwmoa.org/showthread...t=#post1009532

  4. #4
    Cranking a K75 with a feeble battery will almost always stick the starter relay contacts. Back in their heyday this happened to enough people every spring after a winter layaway that I got a lot of panic calls about the issue. So many that even non-mechanical Voni could answer the question as soon as they said, " I tried to start my K75 and it just keeps cranking." She could instantly say "disconnect the ground cable at the side of the transmission or either battery cable as quickly as you can. The starter relay is stuck."
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://web.bigbend.net/~glaves/

  5. #5
    Registered User
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    Apr 2013
    Location
    Southern California USA
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    Unhappy

    Quote Originally Posted by PGlaves View Post
    Cranking a K75 with a feeble battery will almost always stick the starter relay contacts. Back in their heyday this happened to enough people every spring after a winter layaway that I got a lot of panic calls about the issue. So many that even non-mechanical Voni could answer the question as soon as they said, " I tried to start my K75 and it just keeps cranking." She could instantly say "disconnect the ground cable at the side of the transmission or either battery cable as quickly as you can. The starter relay is stuck."
    I hate "iffy" batteries so i usually don't have a low voltage, low CCA issue, but this makes me think i need to stash the correct hex key in the top box for quick access to remove the negative cable connection at the transmission.
    Last edited by chunk; 10-20-2019 at 02:32 PM.

  6. #6
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    Woodbury, MN
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    Too much time has passed

    Quote Originally Posted by vark View Post
    Time flies. Isnít this the same problem you had previously?

    https://forums.bmwmoa.org/showthread...t=#post1009532
    A faint thought in the back of my damaged memory indicates that I did deal with this exact problem many years ago.

    rickt

  7. #7
    Quote Originally Posted by r65lsk75c View Post
    A faint thought in the back of my damaged memory indicates that I did deal with this exact problem many years ago.

    rickt
    No worries. None of us is getting any younger. I forget plenty these days...

    I see from your handle that you own/owned both an R65LS and a K75. These are the two bikes currently at the top of my short list. If you have a chance, any general feedback or impressions you can offer comparing the two would be most welcome, particularly with respect to size, seat height, handling, etc. Thanks.

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