vacuum hose routing

Discussion in 'Engine, Fuel and Exhaust' started by skullmandan, Oct 19, 2014.

  1. skullmandan

    skullmandan Member

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    i removed the carb off of my 95 1200 sportster and there is a metal box with 2 electrical wires and a vacuum hose going to it. it is mounted right under the gas tank behind the carb. the vacuum hose comes out of this box and Y's off. one part of the Y goes to the base of the carb nipple. the other part of the Y the po plugged it off with a bolt. where did this plugged hose go to? do i leave it plugged? can i get rid of the box?
    what carb do i have?
    i looked for a name on it but all i can find is harley davidson on it. i took some pics of the carb. one pics shows some numbers. thanks for any help..........dan
     

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  2. Jack Klarich

    Jack Klarich Expert Member

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    The other hose may have gone to a vacuum @ the petcock
     
  3. Breeze3at

    Breeze3at Well-Known Member

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    The piece with 2 wires and a vac. hose should be the VOES (vac. operated electrical system), but I've not seen one that is a box. Usually a cone shape.
    The stock petcock was vac. operated, and had a line going to the manifold or a "T". See if there is a hose on your petcock. If not, that is probably why you have the plugged line. Your carb is a Keihn CV (constant velocity), a good carb for all around application. Your carb has had the fuel inlet elbow replaced. Original was plastic & brass and easy to break. Yours is solid brass (good thing).
     
  4. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    The voes sends electronic signals to the ignition module to tell it when to use full advance based on the amount of vacuum in the carb it is best to have the voes in the system or the bike will not run very well at times
    It is not unusual for a vacuum operated petcock to be replaced with a high flow petcock and the end of the vacuum pipe to be plugged with a screw
    Best thing to do would be to replace the vacuum pipe with a single pipe from carb to voes and eliminate the t

    Brian
     
  5. skullmandan

    skullmandan Member

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    you guys are awesome!!
    yes there is a manual petcock on her. so that explains that.
    going to run a vacuum hose from the carb to the VOES and get rid of the Y. less chances of a vacuum leak.
    sorry on the description of the VOES its really not a box. at first i thought it was a coil. but coil dont have vacuum hoses connected to it. tried to do a pic of it. the bike is in the shed and my phone dont have a flash.
    thank you guys very much for the info and links.............dan (SOLVED)
     
  6. Breeze3at

    Breeze3at Well-Known Member

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    Well Dan I'll give a Thank You to you for the follow up. Too often we don't get feedback that lets us know if our ideas helped or not.
     
  7. HDDon

    HDDon Experienced Member Contributor Retired Moderators

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    You said that the hose that is not blocked off goes to the base of the carb. I believe the hose would go to the nipple that you can see in the last picture, just below the top cap (black plastic). This is where the vacuum is created. If you're talking about the nipple at the base of the carb this is the for the overflow of the float bowl.
     
  8. skullmandan

    skullmandan Member

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    the vacuum hose in question goes to the vacuum nipple at the base of the carb. the hose going into the nipple has a 45 degree bend and is all cracked.
    the vacuum hose in question starts at the VOES runs to the carb then has a plastic Y part of the Y goes to the base of the carb and the other part of the Y goes to the petcock area but is plugged with a bolt.
    i know a pic will explain it better. i will see what i can do..
    ps.. i know the VOES doesnt pull the vacuum (the carb does) but it was easier for me to explain where the single vacuum hose started then Y'ed off. if it started at the carb and then Y'ed off i would have gone that way with it.............dan
     
  9. tourbox

    tourbox Senior Member

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    HDDon is correct in post #7. The Vacuum line should Not go to the bottom of the carb.(float bowl). It goes where he said.
    tourbox
     
  10. Breeze3at

    Breeze3at Well-Known Member

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    Are we interpreting "base" of carb differently in different minds? Base of carb = point of attachment to intake manifold, or Base of carb = float bowl? I see the overflow/drain tube nipple in the far right photo Don referenced.