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how does jet number relate to hole diameter? Where's the

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    how does jet number relate to hole diameter? Where's the

    math? What's the math?

    BS follows

    scalded cat, effing airbox, jet set, tire trick, headlights 'I like to call them hooters', Steve Martin IIRC GS1000G

    1) GS1000GT runs like scalded cat relative to my FT500. Finally got her out of the barn. Handles nice too. Starts easy. Pulls good. No non-funny sounds. She's got some wierd wizzy exhaust note, sounds like glasspacks.

    2) effing airbox. I'll buy a set of pods before I do that again

    3) re: '2' I'll need bigger jets. How does the number relate to the diameter of the hole in these things?

    4) sound tire, no dry rot, not that old, but it leaked around the rim edge. Let air out, beat bead free with deadblow hammer, cleaned bead and rim with old sock and soapy water. Seal is now good. Just need a new valve stem (schraeder valve good, stem to rim seal rotted, original stem?) Trick let me try out the bike today.

    5)Could only ride up and down the loading dock but got to 7000RPM in first. No headlight. It's in the fairing that's not been remounted yet. Airbox took sl long to fit that it got dark and cop gave me the stink eye as I was about to pull out in front of the building with no helmet and no lights. Can't wait til Friday and more time to work on bike.

    #2
    jet sizes

    Well, the 115 mains on my bike look to have a hole in them approx. 1mm in diameter so maybe 115 is actually 1.15mm ??? or maybe the number is some measurement of flow, like 115 cc's per second. Interesting question!

    If you went with a stock airbox and exaust, it doesn't make sense that you'd need to rejet. That is par for the course with pods and aftermarket pipes.

    Comment


      #3
      the jet number is how many cc's of fuel per minute they will flow under test conditions. a 200jet will flow twice as much fuel as a 100 jet. Though if I remember my math right, the 200 jet will only be a third bigger than the 100 jet.
      You'd have to be crazy to be sane in this world -Nero
      If you love it, let it go. If it comes back....... You probably highsided.
      1980 GS550E (I swear it's a 550...)
      1982 GS650E (really, it's a 650)
      1983 GS550ES (42mpg again)
      1996 Yamaha WR250 (No, it's not a 4 stroke.)
      1971 Yamaha LT2 (9 horsepower of FURY.)

      Comment


        #4
        This link may help

        Comment


          #5
          The chart makes no sense if one column is flow rate and the other is diameter.
          The flow increases as the square of the diameter, pretty much. The bigger dyno would be 2X the flow increase over the smaller yet the MIC numbers only increase by 50%

          IMO the info on that dynojet page is a load of B.S.

          -Bob

          Comment


            #6
            It's not an apple to apple chart, it only shows how two different brands are rated. You need to pick a brand and tune to it. If you bounce back and fourth between the two then it's gets to be a BPITA. If you change brands then it gives you a starting point. Me, I use the Mikuni's.
            1166cc 1/8 ET 6.09@111.88
            1166cc on NOS, 1/8 ET 5.70@122.85
            1395cc 1/8 ET 6.0051@114.39
            1395cc on NOS, 1/8 ET 5.71@113.98 "With a broken wrist pin too"
            01 Sporty 1/8 ET 7.70@92.28, 1/4 ET 12.03@111.82

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              #7
              The way I was told was (for Mikuni) the number indicates flow of fuel in CC's per minute. If you have a 115 main, it will flow 115 CC's of fuel /minute.

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                #8
                SOMEONE TOLD ME IT WAS DRILL BIT SIZES OR SOMETHING

                Comment


                  #9
                  guys... my information is from mikuni. The jet sizes are in CC's a minute :-) Dynojet jet sizes are in mm
                  You'd have to be crazy to be sane in this world -Nero
                  If you love it, let it go. If it comes back....... You probably highsided.
                  1980 GS550E (I swear it's a 550...)
                  1982 GS650E (really, it's a 650)
                  1983 GS550ES (42mpg again)
                  1996 Yamaha WR250 (No, it's not a 4 stroke.)
                  1971 Yamaha LT2 (9 horsepower of FURY.)

                  Comment

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