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1100 ex wont rev above 5000

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    1100 ex wont rev above 5000

    Hi peeps , it revs and runs fine on the stand, but on the road wont rev above 5,000. At 5,000 it just dies, closing the throttle slightly, she comes back to life. Carbs cleaned many times, all ignition system replaced, everything else good, ignition timing, valves etc, recent rebore. Anyone else find the answer to this problem ?? Many thanks.

    #2
    Have you checked the voltage ? if the voltage is low it won't rev high , I had the same problem it was not charging properly, should be at least 14v 14.5v at 5000 rpm , I had a bad wire connection

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      #3
      Is the air box installed?
      1978 GS 1000 (since new)
      1979 GS 1000 (The Fridge, superbike replica project)
      1978 GS 1000 (parts)
      1981 GS 850 (anyone want a project?)
      1981 GPZ 550 (backroad screamer)
      1970 450 Mk IIID (THUMP!)
      2007 DRz 400S
      1999 ATK 490ES
      1994 DR 350SES

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        #4
        Hi peeps, charging fine, new carb rubbers, standard air box, new diaphragms, standard jets. It's got me beat, any ideas ? What would stop the slides lifting fully with the motor under load, could this be the problem ? Many thanks.

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          #5
          If it has a mechanical advance system - pre '83 - the advance may be rusted closed. It's quite common and one reason why they went electronic advance, and the symptoms are 'won't run over 5000'.
          '82 GS450T

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            #6
            Curious - would that mechanical advance issue be the same and limit revs even if not under load?

            Originally posted by John Park View Post
            If it has a mechanical advance system - pre '83 - the advance may be rusted closed. It's quite common and one reason why they went electronic advance, and the symptoms are 'won't run over 5000'.

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              #7
              Originally posted by Simian Major View Post
              Curious - would that mechanical advance issue be the same and limit revs even if not under load?
              Probably not, but it might run pretty rough and ragged or wheezy above 5K. It's been a long time since I had a stuck one in my throttle hand, but I recall that the enthusiasm dropped like a rock at five. The pistons just get too far ahead of the fire behind them.

              In the days of points you had to be careful about how much lube went on the advance mechanism, but with electronic triggers you can have at it. A shot of WD40 every year is a good idea, and I leave the cover off over the winter and the spark plugs loose and give it a shot on the pistons and a few rotations with a wrench every other month. If you have heated storage there's no condensation worries.
              '82 GS450T

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                #8
                Thanks for your thoughts so far, the advance unit is working though hits the 1/4 mark at about 1800 revs, not 2,500 revs, so it seems to get full advance earlier than normal, weak springs ? could this be the problem ? After 2 years trying to sort it, really *@%^$*@%^$*@%^$*@%^$ed off riding with friends and always last on the fast bits of road, apart from the lack of revs a great bike. There is an answer, isn't there ????????? Many thanks.

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                  #9
                  Advancing early is probably weak springs but as long as it gets there the rpm doesn't matter so much. I'd take a good look at the possibility the exhaust system is plugged with something, maybe a rodent stash of nuts. If the exhaust won't pass enough gas, the flow won't be enough to raise the slides fully. Best of luck.
                  '82 GS450T

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                    #10
                    Originally posted by John Park View Post
                    Advancing early is probably weak springs but as long as it gets there the rpm doesn't matter so much. I'd take a good look at the possibility the exhaust system is plugged with something, maybe a rodent stash of nuts. If the exhaust won't pass enough gas, the flow won't be enough to raise the slides fully. Best of luck.
                    That brings back bad memories. I bought a used exhaust system on Ebay for my mx bike. I did a whole bunch of other work on the bike and it ran like crap. The pipe was almost plugged solid with a rodent nest. I could not believe the bike even started. Have you done any plug choppes at 5 k to see if the bike is starving for fuel?
                    1983 gs1100ed restro-mod. 1998 gsxr 1100 almost mint, 2019 kawasaki klx250, 2011 Beta 250 evo trials bike, 2017 Montesa 300rr trials bike, 2021 honda crf250rx woods weapon

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                      #11
                      Hi peeps, plugs are now black, would running rich stall the motor at 5,000 ? Tried all the places online for correct size needles and emulsion tubes , no longer available, anyone else replaced them recently, where can i get them ? Could this be the problem? I've moved the needles up and down a groove , no difference. Many thanks for your help. PS exhaust is clear.

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                        #12
                        Worn emulsion tube will overfuel at anything above idle



                        CMSNL shows them as available
                        Last edited by Big T; 09-02-2020, 04:21 PM.
                        1978 GS 1000 (since new)
                        1979 GS 1000 (The Fridge, superbike replica project)
                        1978 GS 1000 (parts)
                        1981 GS 850 (anyone want a project?)
                        1981 GPZ 550 (backroad screamer)
                        1970 450 Mk IIID (THUMP!)
                        2007 DRz 400S
                        1999 ATK 490ES
                        1994 DR 350SES

                        Comment


                          #13
                          You "cleaned the carbs many times". Evidently the first time was not properly done. Evidently the second might not have been so proper, either. What about the third, and further times? Exactly HOW did you clean the carbs?

                          Running super-rich over 5000 sounds like the rubber plug over the pilot jet is missing.

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                          #2 son: 1980 GS1000G
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                            #14
                            Hi peeps, yes rubber plugs in place, stripped and ultrasonically cleaned 4 times, cleaner and compressed air by me 4 or 5 times. CMSL have had no emulsion tubes X1 for a long time, checked again today, nobody else online either. Anyone know where i can get some ? What about carbs from a later bike ? Lots of work involved ? This problem spoils the bike, hopefully someone can help. Many thanks

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                              #15
                              It's too bad you are still having problems. About your question on later bike replacements. On the orient express site. It lists 1988-2007 600/750 katana, 1986-1992 gsxr 750/1100 among others as the same fitment for rs36 that also fits 1100e. Since I have never tried them , I can't say they will fit, but if I was in your situation I would go to the wreckers with a pair of vernier calipers and do some poking around. Hopefully someone with some first hand experience will chime in.
                              1983 gs1100ed restro-mod. 1998 gsxr 1100 almost mint, 2019 kawasaki klx250, 2011 Beta 250 evo trials bike, 2017 Montesa 300rr trials bike, 2021 honda crf250rx woods weapon

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