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Main Air Jet for 1981 XJ650H

Discussion in 'XJ Technical Chat' started by bunglejyme, Oct 28, 2010.

  1. bunglejyme

    bunglejyme Member

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    My 1981 XJ650H has OEM Hitachi carbs on it. All the jets match OEM specification except for the Main Air Jets. The reference I am using is a Haynes shop manual. Haynes indicates that this jet should be a #80; however, my carbs have #50's instead. Can anyone tell me whether or not I would experience improvement in performance if I change the Main Air Jets back to #80's? If so, couldn't I just drill the #50's out? If so, is the chamfer (cone) at the mouth of the jet bore critical? What is it's function?
     
    bunglejyme, Oct 28, 2010
    #1
  2. Robert

    Robert Active Member

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    I'll politly suggest you sport the $25 and buy the jets you want so if the swap doesn't buy you happiness, you can back up to the jets that work. #50 sounds about right. I just pulled a set out of my 82 650.
     
    Robert, Oct 29, 2010
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  3. iwingameover

    iwingameover Active Member

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    From Len's (chacal) catalog....

    Main Air jet:

    #50: all XJ650 models.

    #70: all XJ700 non-X models, XJ750RL Seca models, and XJ750E-II models.

    #80: all 1981-83 XJ750 North American models and 1981-84 XJ750 UK/European (11M) models.

    NOTE: the Haynes workshop manual for the XJ650 and XJ750 models has the incorrect placement noted for these air jets----the main air jet and pilot air jets are reversed in their picture and caption. Just remember that the main air jet goes directly above the main fuel jet, and is thus located in the "center" of the three holes in this area

    So you should have the #50's.

    Why do you think your air jets need changing?
     
    iwingameover, Oct 29, 2010
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