Home Forums Shifter Karts Need pump around tube placement (has images)

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    • #51424
      Randy McKee
      Participant

      Need some help re-setting the location of the evac tube on my keihin pwk38   (edit: it’s a pwm not pwk) pump around carb.  A while back the tube started to work loose and I tried to put in back in the position I thought was correct (best guess based on marks on the tube).

      It doesn’t really run very well now.  Could be I need to change all of the jetting and test, but I’d rather make sure it’s right before I go to the track again.

      I’m hoping someone has the same carb and can measure the location of the bottom of the tube. See pics and you’ll see where you can probably measure the location of the bottom of the tube in the bowl.  I need depth as well as distance from front of carb.

      Thanks for any help.

      tube depth

      tube depth

      tube distance to front

      tube distance to front

    • #51705
      NOAH PORTILLA
      Participant

      I have the same carb Im new to this so I don’t know if mine is a pump around setup how would I know for sure .. I still have floats, but it does have a fuel return and has one line going to the engine and one going to the carb… I can get pics if that will help before I tear it apart don’t want to do it if I can’t help you… Thanks

    • #51733
      Randy McKee
      Participant

      Noah,

      If it still has the floats, it’s a stock carb.   The floats are removed as part of the pump-around modification and the evac tube is added.  Thanks for the offer on the pics, but your carb doesn’t have that tube.

    • #52058
      NOAH PORTILLA
      Participant

      Randy, Thanks man I did some research after I had replied, sorry I couldn’t help in this situation and thanks for the info on the carb…

    • #52068
      Alan Sheidler
      Participant

      The tube looks to be too high from where it should be in the bowl to me….

      Consider that where it extends to is also the top of the fuel level in the bowl.  Too high, and the carb will be in a permanent flood/rich state.

      [My PWK is in the workshop, and it is late to get a look at it now.  And I am on a 12 hour shift tomorrow.  Will see if I can get a look and a decent photo for you within a couple of days.]

      Edit: I just recalled that I took come pics a while ago for someone else.  No measurements, but see if this helps.  The silver tube upper right corner in the photo is the evac tube.  From my recollection, it extends a little below the bowl seal surface.

      Modified Carb

      PWK

      Mod Carb

      PWK 2. Evacuation tube is near right front corner.

       

    • #52094
      Randy McKee
      Participant

      Alan, thanks for the pics. It looks like your conversion was done by someone different than mine or perhaps because it’s a different carb (I misspoke earlier; my carb is a PWM not ‘K’, so that might explain the differences)

      Your evac is closer to front of carb and as you said it’s might be lower in the bowl. It also appears to be straight (mine curves into the bowl).

      Hmmm…  I think I’ll have to runs some more testing and see if I can narrow it down jetting wise.  It may have been way too fat on the bottom last time out; it felt like I was short-shifting everywhere but shift points were normal rpm wise (and over-rev was fine).  I might try Fastech to see if they have access to the conversion specs.

       

       

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