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Thread: K1200LT Starter Won't Turn Off

  1. #1

    K1200LT Starter Won't Turn Off

    I decided to go for a short ride today since it was gorgeous outside. But my 2000 K1200LT's battery was dead for some reason. So I jumped it from my Jeep and took off. A few miles away I was in a parking lot with the engine still running and had to back up. When I tried to put it in reverse, I could feel the starter motor gears grinding. So I backed out with my feet and went back home. On the way home, I could hear a whining noise (starter?) plus my turn signals didn't work.

    I pulled in the garage, turned off the key, but the starter kept turning the engine even with the key off. So I turned the key back on and left the motor running and grabbed a wrench and disconnected the battery - then turned the motor off.

    Any ideas what might have gone wrong? I have no idea where to start with this problem.

    Thanks - Jack
    2000 K1200LT (87K miles)

  2. #2
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    Sounds like you welded the solenoid contacts together. This happens when you crank the starter too long. New solenoid.

    Sent from my SM-T813 using Tapatalk

  3. #3
    Quote Originally Posted by RadioFlyer View Post
    Sounds like you welded the solenoid contacts together. This happens when you crank the starter too long. New solenoid.

    Sent from my SM-T813 using Tapatalk
    This starter does not really have a solenoid but it is controlled by a starter relay. And these are notorious for having the relay contacts sticking. You will need to disconnect a battery cable to stop the starter and then replace the relay. Sometimes you can unstick the relay by tapping it stoutly with a screw driver handle.
    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/

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    Quote Originally Posted by PGlaves View Post
    This starter does not really have a solenoid but it is controlled by a starter relay. And these are notorious for having the relay contacts sticking. You will need to disconnect a battery cable to stop the starter and then replace the relay. Sometimes you can unstick the relay by tapping it stoutly with a screw driver handle.
    Paul what is the distinction between a solenoid and a relay?

  5. #5
    Quote Originally Posted by RadioFlyer View Post
    Paul what is the distinction between a solenoid and a relay?
    In conventional starter terminology a solenoid is located on the starter. When it is energized it pushes or pulls on a lever which extends the starter nose gear to engage the ring gear/flywheel teeth. At the very end of this action it makes electrical contact which then turns the starter motor on.

    One good definition of a solenoid is:
    "A solenoid is a type of electromagnet, the purpose of which is to generate a controlled magnetic field through a coil wound into a tightly packed helix. The coil can be arranged to produce a uniform magnetic field in a volume of space when an electric current is passed through it. Wikipedia."

    In the BMW classic K bikes (K75, K100, K1100, K1200LT and RS) the starter nose gear and the gear it engages are in constant mesh, coupled by a one-way "sprag" clutch. When the starter is energized the starter spins, the spring-loaded sprags grip and turn the engine. Once the engine is running and turning faster than the starter was turning it the sprags disengage and just slip.

    The starter relay is a simple device to eliminate the need for high starter current to flow through the starter button switch. The relay is a simple electrical switch. Pressing the starter button causes a very low flow of current through a relay coil which then engages the relay contacts. The relay contacts are attached to heavy gauge wire which can be thought of as directly from the battery to the relay to the starter.

    In a sense a solenoid is a specialized type of relay. So a solenoid may be a relay but a relay is not a solenoid. I hope this makes sense.
    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/

  6. #6
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    Quote Originally Posted by PGlaves View Post
    In conventional starter terminology a solenoid is located on the starter. When it is energized it pushes or pulls on a lever which extends the starter nose gear to engage the ring gear/flywheel teeth. At the very end of this action it makes electrical contact which then turns the starter motor on.

    One good definition of a solenoid is:
    "A solenoid is a type of electromagnet, the purpose of which is to generate a controlled magnetic field through a coil wound into a tightly packed helix. The coil can be arranged to produce a uniform magnetic field in a volume of space when an electric current is passed through it. Wikipedia."

    In the BMW classic K bikes (K75, K100, K1100, K1200LT and RS) the starter nose gear and the gear it engages are in constant mesh, coupled by a one-way "sprag" clutch. When the starter is energized the starter spins, the spring-loaded sprags grip and turn the engine. Once the engine is running and turning faster than the starter was turning it the sprags disengage and just slip.

    The starter relay is a simple device to eliminate the need for high starter current to flow through the starter button switch. The relay is a simple electrical switch. Pressing the starter button causes a very low flow of current through a relay coil which then engages the relay contacts. The relay contacts are attached to heavy gauge wire which can be thought of as directly from the battery to the relay to the starter.

    In a sense a solenoid is a specialized type of relay. So a solenoid may be a relay but a relay is not a solenoid. I hope this makes sense.
    Thank you! An education as always.

    Sent from my SM-T813 using Tapatalk

  7. #7
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    I think people have found that the condition occurs most often when the battery is weakened.


    Back in my more-time-than-money days, I had this happen to my 1985 K100RS. I pried open the starter solenoid and sanded the contact points that had welded themselves closed. I intended it to be a temporary fix, but lived with it for as long as I kept the bike.

  8. #8
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    Quote Originally Posted by PGlaves View Post
    In conventional starter terminology a solenoid is located on the starter. When it is energized it pushes or pulls on a lever which extends the starter nose gear to engage the ring gear/flywheel teeth. At the very end of this action it makes electrical contact which then turns the starter motor on.

    One good definition of a solenoid is:
    "A solenoid is a type of electromagnet, the purpose of which is to generate a controlled magnetic field through a coil wound into a tightly packed helix. The coil can be arranged to produce a uniform magnetic field in a volume of space when an electric current is passed through it. Wikipedia."

    In the BMW classic K bikes (K75, K100, K1100, K1200LT and RS) the starter nose gear and the gear it engages are in constant mesh, coupled by a one-way "sprag" clutch. When the starter is energized the starter spins, the spring-loaded sprags grip and turn the engine. Once the engine is running and turning faster than the starter was turning it the sprags disengage and just slip.

    The starter relay is a simple device to eliminate the need for high starter current to flow through the starter button switch. The relay is a simple electrical switch. Pressing the starter button causes a very low flow of current through a relay coil which then engages the relay contacts. The relay contacts are attached to heavy gauge wire which can be thought of as directly from the battery to the relay to the starter.

    In a sense a solenoid is a specialized type of relay. So a solenoid may be a relay but a relay is not a solenoid. I hope this makes sense.


    Simply put;

    A solenoid generally is an electric coil that moves the rod that goes through the coil to do mechanical work.

    A relay uses a small coil to move electrical contacts, either multiple contacts all at the same time or large current contacts where a simple switch would be impractical.




    Why is a starter solenoid sometimes called a solenoid? Because (like Paul said) early starters required a solenoid to engage the starter gear with the flywheel. Most of these also incorporated the starter relay contacts in the same section of the starter. When either of those sections failed, they would just replace the whole section that held the relay contacts and solenoid. They referred to that whole section as the solenoid. Over the years, the terminology stuck with the mechanics, even well after they separated the relay from the starter and mounted them away from the starter (like on your bike). They have since done away with solenoids on many starters and now use the rotation of the starter shaft to drive the gear forward or use constant mesh starters with clutches (like your bike).

    Old habits die hard.




    Last edited by 98lee; 09-12-2020 at 12:09 AM.
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  9. #9
    Dances With Sheep GREGFEELER's Avatar
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    You can buy the Bosch or ETE OEM relays from Amazon for about $40, or order a TE Connectivity brand one from here for less than $25.00 including shipping. At least that was the cost in August of 2018.

    https://www.tti.com/content/ttiinc/e...=true&minQty=1
    Greg Feeler
    Ambassador & amateur K-Bike collector, it seems
    1972 R75/5, 1990 K75, 1990 K1, 1992 K75S, 2003 K1200RS

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