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Has anyone had success correcting high fuel consumption?

Discussion in 'XJ Technical Chat' started by tabaka45, Apr 9, 2013.

  1. tabaka45

    tabaka45 Well-Known Member

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    Thanks. I'm pretty happy. Now on to changing the strut seals.
     
  2. Scottyb321 @gmail.com

    Scottyb321 @gmail.com Member

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    Hi there! I recently had some carb work done by a real idiot. Couldn't even get the bike to fire after he worked on it so I took it to another guy who was legit. He got it to run, but it's burning super rich. He suspects that the 2 jets located beneath the diaphragms were installed in the wrong holes. He was unable to verify because the first guy I hired super glued the rim of the diaphragms down! Anyway, I finally got the diaphragms out and have access to the 2 screws/jets.

    Can anyone tell me the correct placement for each, or better yet have a picture of what they should look like? I don't want to reverse them just to find out that wasn't the problem. It is likely though because several of the other jets were reinstalled in the wrong place.

    I have a 1981 Maxim 650.

    Please help!


     
  3. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    HITACHI MAIN AIR JETS:

    #50: all XJ650 models except Police models.

    This jet has the smaller passage hole and it goes in the CENTER of the three threaded holes under the diaphragm.


    HITACHI PILOT AIR JETS:

    The pilot air jets on all Hitachi HSCxx series carbs are located under the vacuum piston diaphram, and are a small, brass "headless" screw-in jets. On some model carbs, these air jets live under a small, curved "cover plate" which is retained by a special shouldered screw (most later-model Hitachi carbs seem to have dispensed with this air jet cover plate, although its threaded mounting hole still remains in the carb body).

    Replacement Hitachi pilot air jets are now available for these model carbs, in both their original sizes and in optional "tuning" sizes for use with pod filters or other special tuning purposes.

    #195: all 1980-81 all XJ650 North American models, all 1982 XJ650RJ and RJC Seca, all 1980-82 XJ650 UK/European (4K0 and 4K1) models, and all XJ650 Police (37G) and XJ750 Police (24L and 37H) models.

    This #195 jet has the larger passage hole and it goes in the FRONT/FORWARD (towards the cylinder head) of the three threaded holes under the diaphragm.



    The REAR (towards the rear of the bike) threaded hole under the diaphragm cover is used for an air jet cover plate hold-down screw. Not all Hitachi carbs used the air jet cover plate, so the rearward-most hole is not used for anything, in that case.
     
  4. Rooster53

    Rooster53 Well-Known Member Premium Member

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    Courtesy of RickCoMatic

    You need to look and see that you have not mixed-up the placement of any of the Jets.
    BOTH >> FUEL and AIR *
    * (The AIR Jet mix-up being a common mistake due to a misprint in the Data Section of Haynes.)

    Proper AIR Jet Placement:
    [​IMG]
     
  5. hogfiddles

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

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    I know of at least two people who found the excessive fuel consumption was due to worn emulsion tubes. The tops had worn open where the slide needle goes down in. Replacing the tubes solved the problem.

    Dave Fox
     
  6. Scottyb321 @gmail.com

    Scottyb321 @gmail.com Member

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    So then according to the advice mentioned above, it appears my jets are backwards, right? It said the #50 should be in the middle of the 3 holes. The center hole on mine is clearly occupied by the #95 jet.

    You guys could be a God-send for sure if that's right!

     

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