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  • RPM/Speed

    Ok everybody, what RPM does your bike run at when doing 60 mph? I've been thinking of doing the 750/850 final drive change, but the fact that my bike is a basket rebuild makes me question some of the parts that were installed by the P.O. It seems to me that 3900-3950rpms at 60 mph is a bit low! I was wondering what other bike run at so I can get a comparison. I picked 60 mph because it was a nice even number.
    1979XS1100SF
    K&N's and drilled airbox
    Jardine 4in1
    Dunlop Elite 3's
    JBM slide diaphragms
    142.5 main jets
    45 pilot jets
    T.C.'s fusebox & SOFA
    750/850 FD mod.
    XV 920 Needle Mod.
    Mike's XS plastic floats set at 26mm
    Venture Cam Chain Tensioner

  • #2
    4K @ 60
    80 SG
    81 SH in parts
    99 ST1100
    91 ST1100

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    • #3
      3100 rpm at 60 mph. 850 final drive installed.
      79 F full cruiser, stainless brake lines, spade fuses, Accel coils, modded air box w/larger velocity stacks, 750 FD.
      79 SF parts bike.

      Comment


      • #4
        RPM'S

        I'm turning 3500 at 60 mph with the 750 rear end conversion.

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        • #5
          RPM/MPH

          Thanks, that answers my question. I guess the final drive is original.
          1979XS1100SF
          K&N's and drilled airbox
          Jardine 4in1
          Dunlop Elite 3's
          JBM slide diaphragms
          142.5 main jets
          45 pilot jets
          T.C.'s fusebox & SOFA
          750/850 FD mod.
          XV 920 Needle Mod.
          Mike's XS plastic floats set at 26mm
          Venture Cam Chain Tensioner

          Comment


          • #6
            I have the 750 FD swap, and I run 3500 in 5th at 60MPH.

            Comment


            • #7
              Originally posted by red bandit
              3100 rpm at 60 mph. 850 final drive installed.
              You have the lowest rpm at 60. Is the 850 final drive the difference, or do you have a 17 or 18" wheel too? And what tire size?

              What ever you have to make it turn 3100 at 60 I need that too.

              Comment


              • #8
                Don't know why mine is so low. I've clocked my speedo with a couple diff. newer vehicles. My rear tire is a Dunlop Elite 2 MT90 B17 76H Before the 850 FD swap I was running about 3600-3700 rpm at 60 mph. As far as I know the 750/850 are the same. I checked the ratio before I put the 850 on and it was what ever the 750 was. I have plenty of power to pass at 60 in 5th, course it's more fun to drop to 3rd. I get 39-40 mpg, doesn't matter if I run 60 or 85.
                79 F full cruiser, stainless brake lines, spade fuses, Accel coils, modded air box w/larger velocity stacks, 750 FD.
                79 SF parts bike.

                Comment


                • #9
                  The stock FD is a 3.3:1 ratio, while the 750 and 850 FD's are 2.9:1.
                  I think I have a loose screw behind the handlebars.

                  '79 XS11 Standard, Jardine 4/1, Dyna DC1-1 Coils, 145 mains, 45 pilots, plastic floats - 25.7mm, XV920 fuel valves, inline fuel filters, speed bleeders, Mikes XS pods, spade-type fuse block, fork brace, progressive fork springs/shocks, manual petcocks, 750 FD, Venture cam chain tensioner, SS brake lines

                  Comment


                  • #10
                    Ok

                    Dunlop Elite 2 MT90 B17 76H is a 17" tire so your running a 17" wheel. Good, because I have a 17 sitting right here waiting for me to get a 750 FD and install them at the same time.

                    That tire is the same as 130/90/17

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                    • #11
                      If I remember correctly, the 17" wheel is the stock standard size, so I wouldn't be gaining as much in gear ratio with my 79SF. Therefore a slightly higher RPM/lower MPG. Can a 17" wheel be put on a SF? My gas milage is hovering around 33-34 mpg. I will be putting Elite 3's on soon I hope. The size would be the MT90-16's I believe. Like everyone else I am after the Holy Grail of Gas Milage.
                      1979XS1100SF
                      K&N's and drilled airbox
                      Jardine 4in1
                      Dunlop Elite 3's
                      JBM slide diaphragms
                      142.5 main jets
                      45 pilot jets
                      T.C.'s fusebox & SOFA
                      750/850 FD mod.
                      XV 920 Needle Mod.
                      Mike's XS plastic floats set at 26mm
                      Venture Cam Chain Tensioner

                      Comment


                      • #12
                        Originally posted by Toolmaker Tim
                        If I remember correctly, the 17" wheel is the stock standard size, so I wouldn't be gaining as much in gear ratio with my 79SF. Therefore a slightly higher RPM/lower MPG. Can a 17" wheel be put on a SF? My gas milage is hovering around 33-34 mpg. I will be putting Elite 3's on soon I hope. The size would be the MT90-16's I believe. Like everyone else I am after the Holy Grail of Gas Milage.
                        Mines a special I'm putting the 17 on. I been told I need to get dust cover and spacer that goes with it.

                        Comment


                        • #13
                          If I'm understanding correctly, the only thing changed is the dust cover and a spacer to go to a 17? Yeah Yeah, I know, but if you use words with one syllable it's easier for me to understand
                          1979XS1100SF
                          K&N's and drilled airbox
                          Jardine 4in1
                          Dunlop Elite 3's
                          JBM slide diaphragms
                          142.5 main jets
                          45 pilot jets
                          T.C.'s fusebox & SOFA
                          750/850 FD mod.
                          XV 920 Needle Mod.
                          Mike's XS plastic floats set at 26mm
                          Venture Cam Chain Tensioner

                          Comment

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