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Thread: 91 K75S Barn Find

  1. #1
    R69S,R75/5,R90/6,K75C&S
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    91 K75S Barn Find

    Recently found a 91 K75S w/13k miles. Itís been idle since 2008 so Iíll be chipping away at the various well documented gotta doís. Previous owner had their local BMW shop attempt to bring it back to life with a new fuel pump & kit but a fuel leak and the rapidly escalating invoice provoked the sale. Upon receiving the bike, I put a gallon of fuel in, installed a new Westco Battery, a new Starter Relay, and gave it a whirl. To my surprise, it started immediately and purred like a K75 should. After 10 min or so I killed it as fuel was leaking out both sides of the tank. Interestingly, the starter continued to churn, so I disconnected the batt. I whacked the new starter relay and started it again and upon shutting it down, same thingÖ..kept chugging. So Iíll be trying to find whatís causing the relay contacts to weld, given the batt is new and fully charged and the relay is new as well. Any thoughts/ideas from the Brick Brain Trust would be appreciated.
    Upon removal of the tank no obvious holes were found. The fuel appeared to be coming from the fuel sender mounting point, so now Iím in the process of replacing the corroded fuel sender and oíring and will complete a leak check next.
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  2. #2
    3 Red Bricks
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    Welcome to the Forum!

    Great find!

    Make SURE new battery is fully charged. Check voltage across the battery terminals while cranking.

    Check condition of ground wire from battery to bolt on side of transmission just above shift lever.

    Check the voltage to the large wire that leads to the relay from the battery. Should be battery voltage.

    Then check voltage to starter while cranking. Should not be lower than 10V.

    Check the voltage to each of the small wires going to the relay while cranking. Should not be lower than 10V. This could be a sign very dirty ignition or starter button contacts.

    Check voltage at fuse#1 key on. Should be within .5v of battery voltage.


    The fuel leak is probably the O-ring (cheap) 62 16 1 459 608 GASKET RING $8.42, unless you can see something wrong with the sender (expensive) $306.


    Get back to us with results.



    Last edited by 98lee; 12-17-2021 at 02:19 PM.
    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  3. #3
    Registered User mlytle's Avatar
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    www.motobrick.com is the best sources for all questions/info brick related.

    Here is 75s full refresh thread.
    http://www.motobrick.com/index.php?topic=7810.0
    Marshall
    92 K75s, 94 K75s, 09 K1300s

  4. #4
    Recalculating..... veefore's Avatar
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    Great looking machine! Iím attaching a thread I started when I pulled my barn find 93í out of hibernation last year. I had more fun on this than my wethead this year, lol.
    https://www.bmwsporttouring.com/topi...1-the-project/
    2015 R1200RT, 1993 K75s

  5. #5
    R69S,R75/5,R90/6,K75C&S
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    91 K75S Barn Find

    Replaced very rusty fuel level sender & Oíring as well as the battery ground strap, and the starter run on issue is gone. The fuel leak is also gone. I cleaned the gas tank and replaced the fuel filter as well while I was in there. Iíve ridden the bike around the neighborhood and it seems to be running fantastic with great clutch feel, shifting, stopping etc. ABS light is blinking, so Iíll take a brief dive into it, but not overly concerned.

  6. #6
    R69S,R75/5,R90/6,K75C&S
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    Barn Find K75S

    Quote Originally Posted by 98lee View Post
    Welcome to the Forum!

    Great find!

    Make SURE new battery is fully charged. Check voltage across the battery terminals while cranking.

    Check condition of ground wire from battery to bolt on side of transmission just above shift lever.

    Check the voltage to the large wire that leads to the relay from the battery. Should be battery voltage.

    Then check voltage to starter while cranking. Should not be lower than 10V.

    Check the voltage to each of the small wires going to the relay while cranking. Should not be lower than 10V. This could be a sign very dirty ignition or starter button contacts.

    Check voltage at fuse#1 key on. Should be within .5v of battery voltage.


    The fuel leak is probably the O-ring (cheap) 62 16 1 459 608 GASKET RING $8.42, unless you can see something wrong with the sender (expensive) $306.


    Get back to us with results.

    Thank you for the help, Lee! Much appreciated! Running sweet now!



    Thank you for the help, Lee! Much appreciated! Running sweet now!

  7. #7
    3 Red Bricks
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    When your ready to address the ABS, I would ask that you start another separate thread on that one. This will help others when they are searching for a similar problem.

    Please include the year and model (K75S) in the title of the thread.

    There is a good chance that all it needs is to be reset. They are pretty easy to troubleshoot.




    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  8. #8
    Registered User
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    Congratulations! I would love to find such a project since I have never owned or riden any K series cycles and the K75 is my favorite among them.

    Best of luck with the rest of the revival project.

    Be well, ride safely.

    RK

  9. #9
    R69S,R75/5,R90/6,K75C&S
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    K Bikes

    Quote Originally Posted by miseenscene View Post
    Congratulations! I would love to find such a project since I have never owned or riden any K series cycles and the K75 is my favorite among them.

    Best of luck with the rest of the revival project.

    Be well, ride safely.

    RK
    Thanks for chiming in. Iíve been a long time airhead guy but stumbled on and purchased a 1 owner 87 K75C w/12k miles last summer and have enjoyed it immenselyÖ.so much so that I started to search for an S and found the purple one in Wisconsin and had it shipped here. Sadly, I purchased both of these K75ís from the widowís of the original owners, so it adds something special to the experience. I feel obligated to bring them back to life and enjoy them like the original owners did.

    Iím only 7 months into my K75 experience, but Iím smitten. While I try to ride all of my bikes weekly throughout the riding season, the Kís are my more oft chosen steed of late.
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  10. #10
    Dances With Sheep GREGFEELER's Avatar
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    Quote Originally Posted by motiv8ed View Post
    Thanks for chiming in. Iíve been a long time airhead guy but stumbled on and purchased a 1 owner 87 K75C w/12k miles last summer and have enjoyed it immenselyÖ.so much so that I started to search for an S and found the purple one in Wisconsin and had it shipped here. Sadly, I purchased both of these K75ís from the widowís of the original owners, so it adds something special to the experience. I feel obligated to bring them back to life and enjoy them like the original owners did.

    Iím only 7 months into my K75 experience, but Iím smitten. While I try to ride all of my bikes weekly throughout the riding season, the Kís are my more oft chosen steed of late.
    "While I try to ride all of my bikes weekly throughout the riding season, the Kís are my more oft chosen steed of late." Anyone who has ever owned a classic K-bike, and especially a K75, completely understands that statement.
    Greg Feeler
    2022 BMW MOA "Wander Farther" Rally Co-Chair
    Ambassador
    1972 R75/5, 1990 K75, 1990 K1, 1992 K75S, 2003 K1200RS

  11. #11
    R69S,R75/5,R90/6,K75C&S
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    K75

    Quote Originally Posted by GREGFEELER View Post
    "While I try to ride all of my bikes weekly throughout the riding season, the Kís are my more oft chosen steed of late." Anyone who has ever owned a classic K-bike, and especially a K75, completely understands that statement.
    Hi Greg, seeing your location, you must recognize my location in the pic. Good to see thereís at least one other air/brick head in the area.

  12. #12
    Recalculating..... veefore's Avatar
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    Quote Originally Posted by GREGFEELER View Post
    "While I try to ride all of my bikes weekly throughout the riding season, the Kís are my more oft chosen steed of late." Anyone who has ever owned a classic K-bike, and especially a K75, completely understands that statement.
    100%! The K75s gets the nod most times when I head out to the garage. Not quite sure what it is but it is my go to for errands, most running around, and a few journeys this past year.
    2015 R1200RT, 1993 K75s

  13. #13
    Dances With Sheep GREGFEELER's Avatar
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    Quote Originally Posted by veefore View Post
    100%! The K75s gets the nod most times when I head out to the garage. Not quite sure what it is but it is my go to for errands, most running around, and a few journeys this past year.
    Maybe it's the way a K-bike starts so quickly that is seems you haven't even fully depressed the starter button. For me, starting an airhead is like waking something that was sleeping, but starting a K-bike seems like it was already ready to go and just waiting on you. .
    Greg Feeler
    2022 BMW MOA "Wander Farther" Rally Co-Chair
    Ambassador
    1972 R75/5, 1990 K75, 1990 K1, 1992 K75S, 2003 K1200RS

  14. #14
    Registered User
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    Quote Originally Posted by GREGFEELER View Post
    Maybe it's the way a K-bike starts so quickly that is seems you haven't even fully depressed the starter button. For me, starting an airhead is like waking something that was sleeping, but starting a K-bike seems like it was already ready to go and just waiting on you. .
    same with an oilhead, just doesn't start as easily as a K75.

  15. #15
    Debbie's Servant Lee's Avatar
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    Quote Originally Posted by GREGFEELER View Post
    Maybe it's the way a K-bike starts so quickly that is seems you haven't even fully depressed the starter button. For me, starting an airhead is like waking something that was sleeping, but starting a K-bike seems like it was already ready to go and just waiting on you. .
    Lee
    2022 R1250RS
    MOA # 30878
    Past BMW Bikes: 2016 R1200RS, 2011 K1300S, 2003 K1200RS, 1991 K75S, 1987 K75T, 1984 R100RT

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