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  • #1

    Carbs Main Jet question

    Okay... John has been patiently taking me through the carbs on the 81 and explaining things ( I can now take them off and apart and get them back together without parts left over and they work... yea for me)

    The question came up... what exactly do the sizes of the main jets refer to? The size of the hole? The length? Along the same line... is the sizing also true for the pilots?

    I couldn't find the answer in the search... or maybe I just didn't look under the correct thread...

    Thanks for any answers on this one...

    81 SH Something Special
    81 frame, 80 tank and side covers, 79 tail light and carbs, 78 engine, 750 final drive mod, Geezer rec/reg, 140 mains, LH wheels
    ☺

    79 SF MEAUQABEAUXS
    81SH Nor'eas tah (Old Red)
    80 LG Black Magic
    78 E Standard Practice


    James 3:17

    If I can make at least one person smile, or pee their pants a little, or maybe spit out their drink; then my day is not wasted.

    “Alis Volat Propriis”

    Yamaha XS 1100 Classic
    For those on FB
    Tags: None
  • #2
    hole

    they do indeed refer to the hole size.
    1982 XJ 1100
    going strong after 60,000 miles

    The new and not yet improved TRIXY
    now in the stable. 1982 xj11, 18,000miles

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    • #3
      OR...

      Does it have to do with flow rate?

      I found a site that linked a 28 main jet with a flow rate of 28 CC/minute... with a .48 mm diameter hole.

      Is this consistent with the main jets on the XS?
      (well... other than the size)
      81 SH Something Special
      81 frame, 80 tank and side covers, 79 tail light and carbs, 78 engine, 750 final drive mod, Geezer rec/reg, 140 mains, LH wheels
      ☺

      79 SF MEAUQABEAUXS
      81SH Nor'eas tah (Old Red)
      80 LG Black Magic
      78 E Standard Practice


      James 3:17

      If I can make at least one person smile, or pee their pants a little, or maybe spit out their drink; then my day is not wasted.

      “Alis Volat Propriis”

      Yamaha XS 1100 Classic
      For those on FB

      Comment

      • #4
        they do indeed refer to the hole size.
        Thanks! That helps... but I am really looking for relation to the numbers.

        Probably just seems nitpicky to some... but I just like to know "why".

        So... bigger number, bigger hole... this I understand... but what exactly does 110, 115 etc. refer to?

        Is it the flow rate?
        81 SH Something Special
        81 frame, 80 tank and side covers, 79 tail light and carbs, 78 engine, 750 final drive mod, Geezer rec/reg, 140 mains, LH wheels
        ☺

        79 SF MEAUQABEAUXS
        81SH Nor'eas tah (Old Red)
        80 LG Black Magic
        78 E Standard Practice


        James 3:17

        If I can make at least one person smile, or pee their pants a little, or maybe spit out their drink; then my day is not wasted.

        “Alis Volat Propriis”

        Yamaha XS 1100 Classic
        For those on FB

        Comment

        • #5
          Found it

          http://www.xs11.com/forum/showthread.php?s=&threadid=86


          makes me wonder about the other info I found earlier regarding the flow rate and the .48 mm hole though.

          Still open to suggestions, opinions and anything helpful...
          81 SH Something Special
          81 frame, 80 tank and side covers, 79 tail light and carbs, 78 engine, 750 final drive mod, Geezer rec/reg, 140 mains, LH wheels
          ☺

          79 SF MEAUQABEAUXS
          81SH Nor'eas tah (Old Red)
          80 LG Black Magic
          78 E Standard Practice


          James 3:17

          If I can make at least one person smile, or pee their pants a little, or maybe spit out their drink; then my day is not wasted.

          “Alis Volat Propriis”

          Yamaha XS 1100 Classic
          For those on FB

          Comment

          • #6
            Hey WildKat,

            I'm surprised John hasn't gifted you with his wisdom on this topic!?

            The problem with what you found out about the earlier jets is probably due to a different company, type, style of jet and carb.

            As you found in the tech tips, the Mikuni jets are labelled according to their size, which does affect their flow rate of course.

            What the actual flow rate is per size and change I don't know, it may be listed somewhere on the "NET", but haven't looked for it.

            Remember, curiosity is good, but it also killed the "Cat"!
            T.C.
            T. C. Gresham
            81SH "Godzilla" . . .1179cc super-rat.
            79SF "The Teacher" . . .basket case!
            History shows again and again,
            How nature points out the folly of men!

            Comment

            • #7
              Even Gurus need a break

              from others' eternal quest for knowledge... I understand this... we have kids.

              Thanks T.C.! I never thought about them being different makes (brands, styles, etc). I assumed (yeah, I know) that it was a universal measurement.

              Remember, curiosity is good, but it also killed the "Cat"!
              That's why Cats have nine lives...
              81 SH Something Special
              81 frame, 80 tank and side covers, 79 tail light and carbs, 78 engine, 750 final drive mod, Geezer rec/reg, 140 mains, LH wheels
              ☺

              79 SF MEAUQABEAUXS
              81SH Nor'eas tah (Old Red)
              80 LG Black Magic
              78 E Standard Practice


              James 3:17

              If I can make at least one person smile, or pee their pants a little, or maybe spit out their drink; then my day is not wasted.

              “Alis Volat Propriis”

              Yamaha XS 1100 Classic
              For those on FB

              Comment

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