Speedo drive gear ratios

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  • John Kat
    Forum Sage
    • Oct 2010
    • 1433
    • France
    #1

    Speedo drive gear ratios

    Has anyone measured the various gear ratios of the different speedo drives?
    I'm asking the question as I've fitted a 17" GSXR wheel ( with it's speedo drive) to my 1100 kat.
    Will my Kat speedo indicate the correct speed?
    What about using the 18" wheel and speedo from the first generation GSXRs?
    sigpicJohn Kat
    My bikes: CB 77, GS 1000 ST Cafe Racer with GSXR 1052 engine, GS 1000 ST, XR 41 Replica with GS 1085 engine,
    GS 1100 SZ Katana with GS 1135 EFF engine, KTM Superduke 1290 R 2020
    Tags: None
    • Guest
      #2
      I believe that if you match the speedo gear drive with the right wheel, you will be OK. The ratio is most probably 2240:60.

      I have found this on another site:

      2240:60 means that the speedometer cable, coming from the front wheel revolves at 2240 RPM at 60MPH.

      That's a standard in nearly all Asian bikes. The gears in the front wheel are calibrated for the stock wheel, no matter what size it is. If it's stock, the speedo cable will turn at 2240RPM at 60MPH.

      Any generic speedo is made so that it registers for 2240:60. Unless you are using a non-stock wheel, it will read correctly.

        Comment

        • tom203
          Forum Guru
          Past Site Supporter
          • Aug 2010
          • 8925
          • Norway,Maine
          #3
          Me confused! I thought 224/60 was the gear ratio in speedo unit (seems standard on lots of bikes) so depending on tire size the readout unit was fiddled with to give sorta correct reading.
          1981 gs650L

          "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

            Comment

            • John Kat
              Forum Sage
              • Oct 2010
              • 1433
              • France
              #4
              Originally posted by quexpress
              I believe that if you match the speedo gear drive with the right wheel, you will be OK. The ratio is most probably 2240:60.

              I have found this on another site:

              2240:60 means that the speedometer cable, coming from the front wheel revolves at 2240 RPM at 60MPH.

              That's a standard in nearly all Asian bikes. The gears in the front wheel are calibrated for the stock wheel, no matter what size it is. If it's stock, the speedo cable will turn at 2240RPM at 60MPH.

              Any generic speedo is made so that it registers for 2240:60. Unless you are using a non-stock wheel, it will read correctly.
              I knew the Japanese liked standardization but this is amazing
              Many thanks for this great input
              sigpicJohn Kat
              My bikes: CB 77, GS 1000 ST Cafe Racer with GSXR 1052 engine, GS 1000 ST, XR 41 Replica with GS 1085 engine,
              GS 1100 SZ Katana with GS 1135 EFF engine, KTM Superduke 1290 R 2020

                Comment

                • Guest
                  #5
                  Originally posted by tom203
                  Me confused! I thought 224/60 was the gear ratio in speedo unit (seems standard on lots of bikes) so depending on tire size the readout unit was fiddled with to give sorta correct reading.
                  The speedo drive gear combined with the matching wheel/tire will output 2240:60 towards the speedo.
                  If you change the front wheel, you must have the matching drive gear to go with it.

                    Comment

                    • MisterCinders
                      #6
                      Bump with a ratio question. What's a "2:1" ratio fora speedo? How does that relate to the 2240/60 issue? Shopping for a new speedo and there are 1:1 and 2:1 listed.

                      TIA

                        Comment

                        • Big Rich
                          #7
                          1:1 and 2:1 are for Harley and some newer Triumph cycles (and maybe some other newer scoots).

                          It wouldn't be accurate at all on a GS.

                            Comment

                            • growler
                              #8
                              thread resurrection.

                              am i correct in assuming that any speedometer with a 2240:60 ratio will work on my '82 GS850G? saw this on ebay after doing a "2240:60" search:

                              http://www.ebay.com/itm/Drag-Specialties-2240-60-FL-Style-Speedometer-DS243844-/171125742157

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