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Thread: 1993 K75RT stumbles off idle

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  1. #1
    Registered User
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    1993 K75RT stumbles off idle

    Anyone have a idea what would cause a lack of wanting to idle and the engine to stumble off idle. It sounds like it might have a miss at idle, when it idles.
    It runs fine at speed.
    I changed the plugs and drained and filled the tank. The exhaust temps are #1 735
    degrees and #2 around 550 and #3 around 625. The air filter is clean.

  2. #2
    3 Red Bricks
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    Three things that immediately come to mind; a cracked crankcase vent hose, cracked or missing vacuum caps on the throttle bodies, or exhausts valves too tight (this is actually my most likely guess).



    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  3. #3
    Rally Rat
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    +1 Lee

    Try balancing the throttle bodies too.

  4. #4
    3 Red Bricks
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    Quote Originally Posted by timtyler View Post

    Try balancing the throttle bodies too.
    AFTER adjusting the valves.



    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  5. #5
    Registered User argent brick's Avatar
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    Mine has been doing the same thing. I found that the vapor recovery line between the crankcase and the fuel tank was unpluged. Fixing that did not get rid of the problem but it did help.
    Lynn
    MOA #57883
    Current Ride: 1995 K75 Standard
    Past: 1978 Yamaha XS 750, 1976 BMW R60/6

  6. #6
    A bozo on the bus deilenberger's Avatar
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    Quote Originally Posted by argent brick View Post
    Mine has been doing the same thing. I found that the vapor recovery line between the crankcase and the fuel tank was unpluged. Fixing that did not get rid of the problem but it did help.
    That connection shouldn't be made. It was disconnected by BMW, and the fitting into the crankcase should have a rubber cap on it. The tank vent should go to the little funnel on the frame (provides an air gap and allows R&R of the tank much more easily) and from there to ground.

    You may want to look into that..
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

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