Front tire to help stayibility gs750

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  • 81gs7501166
    • Apr 2026

    #1

    Front tire to help stayibility gs750

    I have a 90 90 19 on front.
    Would going to a 100 90 19 help with stability?
    Slight head shake 90ish MPh now.
    Also tire is 12_15 year old. And sit low for a while.
    And what's the correct psi for the forks. 81 gs750e.
    Thanks
  • hillsy
    Forum Sage
    • May 2008
    • 1469
    • Brisbane, Queensland, Australia

    #2
    Are you saying your tyre is 12 to 15 years old? And sat flat for some time?

    You need to replace that. Probably immediately.
    Current:
    Z1300A5 Locomotive (swapped my Intruder for it), GS450 Cafe Project (might never finish it....), XT500 Commuter (I know - it's a Yamaha :eek:)

    Past:
    VL1500 Intruder (swapped for Z1300), ZX9R Streetfighter (lets face it - too fast....), 1984 GSX750EF, 1984 GSX1100EF (AKA GS1150)
    And a bunch of other crap Yamahas....

    Comment

    • JJ

      #3
      Originally posted by hillsy
      Are you saying your tyre is 12 to 15 years old? And sat flat for some time?

      You need to replace that. Probably immediately.
      If not sooner!

      Comment

      • Guest

        #4
        Originally posted by 81gs7501166
        Also tire is 12_15 year old. And sit low for a while.
        Since the front tire is prehistoric, how old is the rear tire? This would be a good time to drain the fork oil and replace the fork springs with some Sonic springs of the correct rate, as well.


        Originally posted by hillsy
        Are you saying your tyre is 12 to 15 years old? And sat flat for some time?

        You need to replace that. Probably immediately.
        I don't know if immediately is soon enough. I wouldn't ride the bike again until the tires were changed out, but that's just me.


        Mark

        Comment

        • roeme
          Forum Sage
          Past Site Supporter
          • Jul 2015
          • 1206
          • Switzerland

          #5
          (...)Slight head shake 90ish MPh now.
          Also tire is 12_15 year old. And sit low for a while.
          ...and all you can think of is changing tire dimensions? Are you trolling?
          #1: 1979 GS 550 EC "Red" – Very first Bike / Overhaul thread        New here? ☛ Read the Top 10 Newbie mistakes thread
          #2: 1978 GS 550 EC "Blue" – Can't make it a donor / "Rebuild" thread     Manuals (and much more): See Cliff's homepage here
          #3: 2014 Moto Guzzi V7 II Racer – One needs a runner while wrenching
          #4: 1980 Moto Guzzi V65C – Something to chill

          Comment

          • Guest

            #6
            Originally posted by roeme
            ...and all you can think of is changing tire dimensions? Are you trolling?
            my thoughts exactly, srsly?

            Comment

            • bwringer
              Forum LongTimer
              Bard Award Winner
              GSResource Superstar
              Past Site Supporter
              Super Site Supporter
              • Oct 2003
              • 17075
              • Indianapolis

              #7
              The correct front tire size for your bike is 100/90-19

              And yes, replace that old hunk of crap tire immediately.

              The correct pressure to run in the forks is "none" -- install a set of Sonic fork springs in the correct spring rate and with fresh fork oil.


              Instability can have many overlapping causes, so a new front tire in the correct size and fork springs will help, but may not fix the problem entirely. It's quite likely you also need steering stem bearings, and you could also have problems in the front end that are actually caused by the rear end -- a bad rear tire, shocks, and/or swingarm bearings.
              Last edited by bwringer; 08-11-2017, 09:03 AM.
              1983 GS850G, Cosmos Blue.
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              • 81gs7501166

                #8
                I'll order a new tire today. Benn looking at perilly.
                Any advise.
                Neck bearings and swing arm replaced when built.
                Only got mabe 1500 miles on them.
                Tires look good no dry rot. Been in basement

                Comment

                • sharpy

                  #9
                  Tryes are stuffed, get a matching set. Get great advice BEFORE u buy a tyre. dont just put any old thing on it. maybe some Bridgestone Battlax BT45 High Performance Tires. 100/90 x19 front and 120/90 x18 rear

                  Comment

                  • roeme
                    Forum Sage
                    Past Site Supporter
                    • Jul 2015
                    • 1206
                    • Switzerland

                    #10
                    Originally posted by 81gs7501166
                    I'll order a new tire today. Benn looking at perilly.
                    Any advise.
                    Neck bearings and swing arm replaced when built.
                    Only got mabe 1500 miles on them.
                    Tires look good no dry rot. Been in basement
                    Alright, as soon as you've got proper new tires on - balanced and inflated properly - you'll have eliminated most of the causes of head shake. The only other things I can think of would be the wheel bearings. Though when it comes to head shake my experience is limited to aforementioned causes.
                    #1: 1979 GS 550 EC "Red" – Very first Bike / Overhaul thread        New here? ☛ Read the Top 10 Newbie mistakes thread
                    #2: 1978 GS 550 EC "Blue" – Can't make it a donor / "Rebuild" thread     Manuals (and much more): See Cliff's homepage here
                    #3: 2014 Moto Guzzi V7 II Racer – One needs a runner while wrenching
                    #4: 1980 Moto Guzzi V65C – Something to chill

                    Comment

                    • 81gs7501166

                      #11
                      Front tire in and it's bout to be hung on a cherry picker!

                      Comment

                      • 81gs7501166

                        #12
                        It's on. Feels much better.
                        No bounce.
                        Much improved grip.
                        Rear is next.
                        Do these 81 gs750 wheels require tubes?
                        Last edited by Guest; 08-20-2017, 11:30 AM.

                        Comment

                        • RichDesmond
                          Forum Sage
                          Past Site Supporter
                          • Jul 2011
                          • 2757
                          • NoVa

                          #13
                          Originally posted by roeme
                          Alright, as soon as you've got proper new tires on - balanced and inflated properly - you'll have eliminated most of the causes of head shake. The only other things I can think of would be the wheel bearings. Though when it comes to head shake my experience is limited to aforementioned causes.
                          Once you get past tires, wobble issues are more commonly caused by problems at the rear of the bike, with worn shocks leading the list.
                          '20 Ducati Multistrada 1260S, '93 Ducati 750SS, '01 SV650S, '07 DL650, '01 DR-Z400S, '80 GS1000S, '85 RZ350

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                          • Gorminrider
                            Forum Sage
                            Past Site Supporter
                            • Aug 2012
                            • 4803
                            • British Columbia, Canada

                            #14
                            and bikes can easily have slightly bent-misaligned stanchions from a prang or drop. I just pranged a bike into the side of a u-turning Pickup truck so I'm learning ins and outs of this lately....
                            it's a good idea to check alignment of wheels

                            Comment

                            • 81gs7501166

                              #15
                              Front tire on,had it to 100,no shake.
                              Rear 120 is hear, hope to install today, taking off a 130.

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