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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
    3 Red Bricks
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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.
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  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
    3 Red Bricks
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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

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