Rear Shock settings question.

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  • GS750GUY
    #1

    Rear Shock settings question.

    When restoring my 78GS750EC I replaced the original leaking rear shocks with a new set of chrome "Progressive type" shocks and since I was working with limited funds did not want to part with additional big bucks for progressive fork springs so when I rebuilt the forks I added a 1" piece of PVC to help stiffen up the fork springs a little bit. The bike had only 11,000 original miles on it so I figured the fork springs could not be in too bad of shape.
    When I ride solo I set my tire pressure at the recommended 24 pounds front and 36 pounds rear and set my rear shocks at their softest setting and this seems to work fine at in-town speeds when just pokin around town. However, when out on two lane black top at 50 to 55 Mph I ocassionally notice a bouncing sensation and I'm having trouble determining if I have my rear shocks set too soft or if the bouncing is coming from the front end.
    The bike does not excessively nose dive on me during stiff breaking so I'm thinking possibly I need to go to a stiffer setting with the rear shocks at higher speeds but I'm not sure how stiff to go.
    Any of you long time experienced riders out there have any insight for me regarding this.
    Appreciate it!!
    GS750GUY
    Tags: None
    • Billy Ricks
      #2
      Pogo effect is usually due to a lack of damping.

        Comment

        • first timer
          Forum Sage
          • Aug 2002
          • 3429
          • Tucson, Arizona
          #3
          you need to do a search on here or the internet on how to properly set your sag for both front and back shocks. That should give you a starting point. Also you need to pick the right fork oil for your weight and riding style. If you give a little more info i am sure some here can help you with that.

          Also suspension set up on these old bike is always fun, since they are 30 years old some times things wear out. Even if you have your suspention set right things like worn swing arm bearings will interfer with the handeling and so will wheel bearings and steering stem bearings. If you don't know how old they are they are probly to old and should be
          replaced.

          Also i would not follow what pressures to set the tires as recomended bike manufacturer, these pressures were based on old tire tech, I would follow what ever pressures are recomended by tire manufacture. It's their tire they designed it and know best.
          78 GS1000 Yosh replica racer project, 82 Kat 1000, 10 990 ADV-R, Some dirt bikes

            Comment

            • first timer
              Forum Sage
              • Aug 2002
              • 3429
              • Tucson, Arizona
              #4
              Originally posted by Billy Ricks
              Pogo effect is usually due to a lack of damping.

              yes but progressive rears are auto damping they have no settings. SO either it's the front with too light fork oil or some thing bad somewhere. but he can start by setting sag at least to see if that helps.
              78 GS1000 Yosh replica racer project, 82 Kat 1000, 10 990 ADV-R, Some dirt bikes

                Comment

                • Billy Ricks
                  #5
                  Originally posted by first timer
                  yes but progressive rears are auto damping they have no settings. SO either it's the front with too light fork oil or some thing bad somewhere. but he can start by setting sag at least to see if that helps.
                  He doesn't have Progressives, he has "Progressive Types." He should set up the sag like you said and go from there. Sag is the difference between the suspension fully extended with the wheel off the ground and then on the ground with your weight in the seat. You can measure the distance between the lower tubes on the fork and the bottom of the triple. At the rear you want to measure from the axle to some point straight up on the frame or the seat edge. 1" of sag works well for hard riding on curvy backroads. For a more plush ride shoot for 1/4 -1/2" more. Set both ends up the same.

                  As for running what the tire manufacturer stamps on the tire, that is bad advice. Those are max pressures for max load. What should be done is to take a cold tire pressure measurement and a hot tire pressure measurement. You want to see about 3 lbs more pressure hot vs cold. Anything more and the tire is heating up too much. Anything less and it's running too cold. Too much pressure also causes a smaller contact patch and a slippery tire.
                  Last edited by Guest; 10-28-2008, 01:23 PM.

                    Comment

                    • Billy Ricks
                      #6
                      The front tire may also be flat spotted if it sat in one position too long with the weight of the bike on it.

                        Comment

                        • Guest
                          #7
                          Tape

                          Stick a small piece of masking tape on one of your front fork tubes about 3 inches above the seal. When you feel the bouncing sensation, take a look to see if it's getting closer/farther from the seal. That way, you'll know if it's the front or rear. I have a hunch it's the rear.

                            Comment

                            • Guest
                              #8
                              Truckin'

                              Originally posted by Billy Ricks
                              The front tire may also be flat spotted if it sat in one position too long with the weight of the bike on it.
                              That will also happen if you leave a dump truck loaded overnight but it goes away when the tires warm up (a few miles).

                                Comment

                                • first timer
                                  Forum Sage
                                  • Aug 2002
                                  • 3429
                                  • Tucson, Arizona
                                  #9
                                  you caught me Billy, thats what i get for trying to do work and play on the GSR at the same time. I need to pay attenion more and assume less that people under stand the tire is stamped with a max pressure and they should find a pressure somewhere in the range the tire gives.

                                  You have good advice.
                                  78 GS1000 Yosh replica racer project, 82 Kat 1000, 10 990 ADV-R, Some dirt bikes

                                    Comment

                                    • Billy Ricks
                                      #10
                                      Originally posted by first timer
                                      you caught me Billy, thats what i get for trying to do work and play on the GSR at the same time. I need to pay attenion more and assume less that people under stand the tire is stamped with a max pressure and they should find a pressure somewhere in the range the tire gives.

                                      You have good advice.
                                      No problem, I do the same. I just kind of skim through posts picking up highlights and go from there. I stick my foot in it all the time like that.

                                        Comment

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