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Main Jet issue

Discussion in 'XJ Technical Chat' started by redneckzombi, Jul 21, 2011.

  1. redneckzombi

    redneckzombi Member

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    So I just picked up a 650 Maxim and my first order of business is cleaning the carbs. One cylinder wasn't firing, and now I know why -- the #4 main jet just fell out as soon as I removed the carb bowl. At first I thought the PO maybe just didn't screw it in tight, but it looks like the tube that the main jet (emulsion tube? I'm pretty new to carburetors) is pushed down farther than the other 3 so that with the copper washer in place the threads on the main jet aren't long enough to reach it. The tube moves freely, but I can't easily pull it back out to where it should be. Is there a trick to this? Is it threaded or just press-fit? My initial thought was to screw something into it and pull, but I don't want to do any damage.
     
    redneckzombi, Jul 21, 2011
    #1
  2. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    Th emulsion tube (a/k/a power valve or main jet) is a push-fit. If you lift up the vac piston (on the airbox side of the carb throat) you can get your finger in there and push it down into place. When it's fully seated, you'll enjoy a satisfying "click" type of sound.........
     
    chacal, Jul 21, 2011
    #2
  3. redneckzombi

    redneckzombi Member

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    Thanks! That's what I wanted to know -- I didn't want to try to push it in place and then find out it was fine-threaded brass and destroy it.
     
    redneckzombi, Jul 21, 2011
    #3
  4. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    Double-check to make sure that there is not an indexing pin just at the bottom of the tube right before the jet. some carbs have them and some don't. If they don't, the tube is smooth all the way around the base. If there is an indexing pin, then the tube will havea slot that needs to be lined up for the pin. Sounds almost like the tube wasn't lined up with the pin so it can't go in far enough. See what's there.

    Dave
     
    hogfiddles, Jul 21, 2011
    #4
  5. RickCoMatic

    RickCoMatic Well-Known Member

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    Use a Metric Cap Screw with the SAME Thread Pitch.
    Extend the Center Nozzle as far as it will go.
    Put the Cap Screw in the Bottom.

    Pull on the Cap Screw while you Push with your Finger.
    (Hint: Polish and Buff the O.D. of the Tube. Lightly Grease the Shouldered-ends with a synthetic gease.)

    Hitachi Carbs are a Tight Press Fit.
    Mikuni Carbs are Slotted and Keyed.
     
    RickCoMatic, Jul 21, 2011
    #5

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