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Almost there, still a rough idle

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    Almost there, still a rough idle

    So...lots of work and she still has a rough idle. 1979 GS850G. Rebuilt air box (twice), it's perfect this time. Valves done. Good spark. New boots to both the air box and the intake (with new intake o-rings). Carbs rebuilt (new o-rings, dipped, the works). The bike is running way better but she still idles rough with the occasional backfire through the carb. Two of the fuel jets are new as they were broken the others are the originals. Floats were all set to factory height. Carbs are synched. I tried to adjust the fuel mixture screws using the best idle method but it doesn't really seem to effect the idle when I am doing it. I would really appreciate any further advice with this, as I've already recieved so much help. It's sooo close.
    Rob
    1983 1100ES, 98' ST1100, 02' DR-Z400E and a few other 'bits and pieces'
    Are you on the GSR Google Earth Map yet? http://www.thegsresources.com/_forum...d.php?t=170533

    #2
    What are your pilot fuel and air screw settings?
    Ed

    To measure is to know.

    Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

    Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

    Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

    KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

    Comment


      #3
      I sarted at stock, 5/8 and 1 1/4. Like I said I tried to best idle them with not much success, # 3 is at about 3/8 and 1 but other than that they are at stock, she seems to idle best there. I don't have a colortune but I'm thinking that might be the best idea.
      Rob
      1983 1100ES, 98' ST1100, 02' DR-Z400E and a few other 'bits and pieces'
      Are you on the GSR Google Earth Map yet? http://www.thegsresources.com/_forum...d.php?t=170533

      Comment


        #4
        I'd try 3/4 open for the fuel screws and 1-1/2 for the air screws. What does your comment about replacing "two of the fuel jets" mean? Are you talking about the pilot fuel screws? If so, did you check the carb bodies for broken tips stuck inside?
        Ed

        To measure is to know.

        Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

        Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

        Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

        KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

        Comment


          #5
          If I try putting the screws out more the bike back fires more. Any believe me those carbs are so clean inside!!.. There were two broken tips when I originally dismantled but there are non in there now, carbs were dipped well, sprayed, and air hosed. Everything is clear.
          Rob
          1983 1100ES, 98' ST1100, 02' DR-Z400E and a few other 'bits and pieces'
          Are you on the GSR Google Earth Map yet? http://www.thegsresources.com/_forum...d.php?t=170533

          Comment


            #6
            fixed

            So I go into the timing again and this time check the points with a multitester. Turns out I am getting power to both points at the same time. So there is a short somewhere. I trace it as far as the harness going towards the tach/speedo and figure this could get ugly so I just unplug the two wires white and black and yellow and hook them directly to the coils by splicing them with the two orange wire from the coils and WHAMO!!! no back firing, no bogging, she ran and pulled like I've never seen her before. If I ever get ambitious I will trace down the actual short..maybe.
            Rob
            1983 1100ES, 98' ST1100, 02' DR-Z400E and a few other 'bits and pieces'
            Are you on the GSR Google Earth Map yet? http://www.thegsresources.com/_forum...d.php?t=170533

            Comment

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