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Thread: 1990 K75RT Electrical problem

  1. #16
    Registered User AntonLargiader's Avatar
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    It really sounds like a bad connection between the alternator+battery and the rest of the bike, or the same on the ground side. Batteries can do strange stuff but if the engine is running it will normally compensate for a bad battery, so it won't shut off. And a dead alternator shouldn't kill the bike or keep it from cranking as long as the battery is good. It's easier to imagine the problem being on the ground side.

    There is a stack of grounds on the left side of the frame backbone toward the front, and you have the battery-to-transmission ground lead. Assuming you have a good engine-to-frame connection, that is your complete ground path.
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  2. #17
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    Nick,


    Just for giggles, do a test:

    Measure your battery voltage across the posts. Key on, kill switch in run.

    Now measure from the back of the #1 (top) fuse (there are two little holes in the back of each fuse that you can put your meter probe into. Use either side.) to the negative batery terminal. Key on, kill switch in run.

    How close are these two numbers? Turn key and kill switch off and then on again and reckeck reading at fuse several times. Do the readings ever differ more .3 volts from the reading straight across the battery?





    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  3. #18
    Nick Kennedy
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    Lee
    Let me do that test tonight
    Thanks for taking a interest in this problem.
    I've never taken the gas tank off, to clean those grounds Anton mentioned; its got the full RT fairing, do I need to remove the fairing first?
    Best Regards

  4. #19
    Quote Originally Posted by nickrides View Post
    Lee
    Let me do that test tonight
    Thanks for taking a interest in this problem.
    I've never taken the gas tank off, to clean those grounds Anton mentioned; its got the full RT fairing, do I need to remove the fairing first?
    Best Regards
    No, the rear of the tank lift up when a couple of circlips are removed (if they are still there - most are not) and then the tank slides back. You need to disconnect the fuel lines and the electrical plug. Lines on the left front; plug at the right rear.
    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. #20
    Nick Kennedy
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    Lee
    I ran your test
    Across the battery with the key on and shutoff switch on it read 12.15v
    Across the fuse it read 12.11v
    What could this indicate?
    Thanks in advance
    Nick

  6. #21
    Nick Kennedy
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    Ok
    So I'm going to make a new Battery - frame ground lead and take off the tank and clean those group of Ground leads Anton mentioned under the tank. I sprayed some contact cleaner into the ignition switch, actuated it several times and then sprayed a little oil in there to loosen it back up.
    Like I said my last resort is taking apart the ignition switch and cut off kill switch, I DO NOT want to break them and that plastic is 29 years old now.

  7. #22
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    Quote Originally Posted by nickrides View Post
    Lee
    I ran your test
    Across the battery with the key on and shutoff switch on it read 12.15v
    Across the fuse it read 12.11v
    What could this indicate?
    Thanks in advance
    Nick
    Nick,


    A difference of more than around .3 volts is an indicator of a possible dirty ignition switch. Lack of a difference does not always indicate that the switch is clean. It could be that that time you turned the switch it made good contact by pushing the crude out of the way. But the chance of it being something other than the switch is higher with the reading you got.

    The battery voltage does seem a bit low. What is it with the switch off?




    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  8. #23
    Nick Kennedy
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    Lee
    Yesterday I took off my tank. Cleaned those 5 grounds connected to the frame, they looked clean and tight. Pulled all the relays- they all looked clean and tight. Pu the bike on a Battery charger for a couple of hours. This morning the battery was at 12.9v. Did not start the bike, snowing too hard.

    So today after work I think I'm going to make a new Battery to frame ground wire and take apart and clean up the ignition switch. I hope that switch cleaning goes OK

  9. #24
    3 Red Bricks
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    Nick,

    While you are making the battery to frame (bolt on transmission above shifter lever) wire, make an additional one from that bolt to the bolt on the frame under the gas tank.

    Try to do the switch cleaning at your kitchen table in a large cake pan. That way, if any of the tiny parts get dropped, you will have an easier time finding them.




    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  10. #25
    Nick Kennedy
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    So the saga continues
    Haven't cleaned the ignition switch yet, I'm leery of breaking it.

    So I've still been riding the bike, hasn't stranded me yet.

    Same problem Start it up and it runs for a minute or so and then shuts off with the ign oil pressure lights half lit. Turn key off and on and it starts right up and runs all day
    Another problem over the last month my starter has stuck on 3X. Battery is new and strong. yesterday I could not find a allen wrench and the starter turned for over a minute. It got warm, not too hot
    So I want to replace the starter relay, euromotoelectric wants $50 for one.
    Question
    Can I pry the top off of it and clean the contacts myself?

    I know I have to clean the ign switch but if I break the tabs off I'm screwed.

  11. #26
    3 Red Bricks
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    Nick,


    The starter relay stuck because it was seeing a low voltage situation.

    Your lights go half dim because they are seeing a low voltage situation.

    As Anton pointed out, it seems that there is a bad connection between the battery (positive or ground) and the bike. That bad connection could be at the terminals, or it could be bad battery cables (like the extension cord that will cut out unless you hold the end just right), a dirty ignition switch etc.

    If you are worried about breaking your ignition switch while trying to clean it, mail it to me and I'll clean it for you. If I break it, I have spares.





    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  12. #27
    Nick Kennedy
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    OK
    Its looks like I need to replace both battery cables AND clean the ign switch.
    I'll do that and let you guys know how it goes!
    Thanks in advance!

  13. #28
    Nick Kennedy
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    So the Big Chicken [ me ] took out the Ign switch last night and took it apart and cleaned it. And got it back together after a few tries.
    Didn't break anything.
    Started the K 75 up and it idled in my shop for 3-4 minutes just fine.
    Hopefully this may be the fix
    Thanks to all and Lee for helping me out with this issue
    I appreciate it very much!

  14. #29
    Nick Kennedy
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    Question number 648
    So why, when the starter relay sticks on, with the key on, doesn't the bike start?
    Its cranking away. This stuff is obviously way over my paygrade.

  15. #30
    Quote Originally Posted by nickrides View Post
    Question number 648
    So why, when the starter relay sticks on, with the key on, doesn't the bike start?
    Its cranking away. This stuff is obviously way over my paygrade.
    Almost always when the relay sticks it is because of a low voltage at the relay due to one of several possible causes. It is also a fact that the LJectronic analog ECU which controlled fuel injection would tolerate lower voltage than the ignition control module. As a result, when voltage dropped the spark would quit before the injectors did. This usually resulted in fuel-wet spark plugs. So even when proper voltage was restored the engine was "flooded" and wouldn't start. I encountered this on numerous occasions on several of our and other's bikes.

    In fact I received phone calls saying "my starter won't quit" and asking "what should I do" often enough every spring that even non-mechanical Voni could tell people to disconnect the ground lead at the transmission or battery. My advice always also advised people to get a sound fully charged battery, to replace the relay (or as a short term fix to rap on it with a screwdriver handle) and to clean or replace the spark plugs because they were probably fuel fouled.
    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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