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Thread: 90 K75S vent hoses

  1. #1
    Registered User jwetering's Avatar
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    90 K75S vent hoses

    Hi Guys;

    Just buttoning the bike up after replacing the clutch and there are two fabric sheathed vent hoses that run along side the right side of the bike.

    One has come off, and it's not obvious where it hooks up to.

    The hose that is still connected smells of oil and gas, so I am guessing that it is the crankcase vent.,

    What is the other one please and where does it connect to please?

    Thanks

    jasper

  2. #2
    A bozo on the bus deilenberger's Avatar
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    Jasper,

    The early K's had two vent lines to the fuel tank that came up the right side to the small spigots on the bottom of the tank. Was was a cap drain (for rain water) the other was the tank vent. This was later modified to a sort of plastic funnel arrangement that mounted to the frame cross-member at the rear of the tank area, and captured whatever came out of both vents - and had a single hose running to the right side near the rear master cylinder.

    Not sure if your '90 would have the single/funnel or still have the dual vents..

    Lee? Paging Lee to the white information phone please!
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders
    '12 R1200R - I love this bike!

  3. #3
    Don is correct. The "funnel" is called an accumulator. Do a search on the forum for the part #. I put one on mine a few months ago. It makes life much easier when installing the fuel tank.
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    Jim McGill
    '87 K100RS
    '04 R1150RT

  4. #4
    Registered User jwetering's Avatar
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    Thanks gents - will lift the tank and look for the connection - probably at the filler cap.

    cheers

  5. #5
    3 Red Bricks
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    Jasper,

    The tank has two 1/4" diameter nipples on the right rear bottom about 3/4 of the way back. The front one is the tank air vent. The rear one is the filler cap rain drain. It runs through the tank to a hole on the left side of the filler flange.

    There are two ways to vent the tank:

    The way BMW originally did it is NOT the preferred way. They ran a hose from the front nipple forward, through a check valve that looks like an emitter on a drip irrigation system, to a nipple on the top front center of the engine block just below the fan. This would put gas fumes (and sometimes raw gas) into your crankcase. NOT good!

    The rear nipple had a hose that dumped to the ground behind the right peg plate.



    The PREFERRED way is to mount the air accumulator/cup/funnel to the frame (see Jim's photo) below the two nipples and hook the hose that originally was the rain drain to the cup. That allows anything that goes into the cup to drain to the ground.

    Then you MUST remove the original tank air vent hose and CAP THE NIPPLE on the block so you don't have a vacuum leak.

    16132307467 AIR ACCUMULATOR $2.15

    If you already have the cup installed MAKE SURE that the nipple on the top front center of the block is capped off.




    The are two other hoses that run along the right side of the bike.

    One is the radiator overflow that runs from the filler neck to the coolant overflow bottle. MAKE SURE there are NO cracks anywhere in this hose!!!! If there are, you will suck air into the radiator.

    The other hose is the hose from the rear brake fluid reservoir to the rear master cylinder.



    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  6. #6
    Registered User jwetering's Avatar
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    Thank you guys/

    I lifted the tank, saw two nipples, one with a hose attached, one without.

    I attached the loose hose to the open nipple, and that was that.

    I don't think I'll bother upgrading to the funnel design - so far I haven't had any trouble.

    The coolant hose and the brake fluid reservoir hose were fine - although I fought with the rear brake setup *all* day. Long story - I don't want to talk about it.

    Looks like tomorrow it will be a runner - not today.

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