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    All Possibilities of hanging high idle

    Okay so, I just need to know all the possibilities of having a high idle after giving the bike a little throttle, high idle being over 3000rpm, and only occurs when given enough throttle to reach a bit over 2000rpm. I can pull the choke rack to knock the idle back down to normal, but sometimes it will just go back up.

    I have checked the intake boots for vacuum leaks and everything seems to be okay. I have disconnected the throttle cable and revved the bike by the carbs throttle and the throttle cable isnt the issue.

    What else could it be? Video for reference.



    I'm gonna have to mess with my fuel mixture screws as the sparks are covered in soot but all 4 do spark, so I'm gonna be adjusting by half a turn each time. They are champion plugs that are cross referenced from the ngk d8ea.
    Ian

    1982 GS650GLZ
    1982 XS650

    #2
    I do have a set of airpods I can put on the bike to see if its a vacuum leak from the airbox but I didnt want to risk overheating the bike from running lean, would this be okay to do just to test out seeing for airbox leaks?
    Ian

    1982 GS650GLZ
    1982 XS650

    Comment


      #3
      Hi, Ian.
      Hope you were happy with the plungers.
      Don't fit the pods. That will screw up the carburation on CV'S big time. Even with a jet kit and dual pods they never run perfect..
      It does sound like a lean condition if opening the choke ( enrichener) steadies the revs.
      It's very difficult diagnosing online but there's varying conditions that will cause the hanging idle and throttle cables and plunger seals which you have eliminated are two of them.
      Air leaks on the intake boots, air leaks on the vac port covers, loose jets, sticking mechanical timing advancer and diaphragm leaks etc are the other usual suspects, even the cam timing a tooth out or restricted fuel supply ( partially blocked fuel filter) can cause this.
      All i can say is work methodically , starting with the fuel supply at the tap and work through the system to eliminate each area.
      You will eventually find the cause if you follow an organised path.
      Mikuni Viton Choke Plunger Seat Renewal.
      VITON Choke plunger seals .KAWASAKI Z1,Z900,Z650,Z1000,Z1R,SUZUKI GS1000,GSXR,RF | eBay

      Air Corrector Jets for Mikuni VM 24, 26 and 28mm carbs .
      https://www.ebay.co.uk/itm/254380193...84.m1555.l2649



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        #4
        Originally posted by zed1015 View Post
        Hi, Ian.
        Hope you were happy with the plungers.
        Don't fit the pods. That will screw up the carburation on CV'S big time. Even with a jet kit and dual pods they never run perfect..
        It does sound like a lean condition if opening the choke ( enrichener) steadies the revs.
        It's very difficult diagnosing online but there's varying conditions that will cause the hanging idle and throttle cables and plunger seals which you have eliminated are two of them.
        Air leaks on the intake boots, air leaks on the vac port covers, loose jets, sticking mechanical timing advancer and diaphragm leaks etc are the other usual suspects, even the cam timing a tooth out or restricted fuel supply ( partially blocked fuel filter) can cause this.
        All i can say is work methodically , starting with the fuel supply at the tap and work through the system to eliminate each area.
        You will eventually find the cause if you follow an organised path.
        What's the vac port cover?

        All I've noticed is over time this problem has got increasingly worse, it used to sit at 2k, now almost 4k. Only seems to happen when the bikes warm but that could be wrong.

        I dont run a fuel filter it's just a fuel line.

        Gonna probably have to check the cam timing just to make sure, but also that mechanical advancement.


        Oh and the plungers work great now, just wish everything else did!
        Last edited by timebombprod; 02-26-2021, 09:45 PM.
        Ian

        1982 GS650GLZ
        1982 XS650

        Comment


          #5
          You say you checked for intake air leaks, I assume you mean the boots themselves are not cracked along thier body.

          Other things to concider:
          - boots old and stiff so dont seal well. boots old and stiff so the clamps have been overtightened and stretched out, and/or the boots deformed.

          - boots separating from the base flange.

          - boot o-rings old and hard. (orings up against the head)

          - (and what got me: ) O-Rings in the enricher(choke) mechanism. HAve to completely break down carbs from the rack to replace these.

          Had 850G for 14 years. Now have GK since 2005.
          GK at IndyMotoGP Suzuki Display... ... GK on GSResources Page ... ... Euro Trash Ego Machine .. ..3 mo'cykls.... update 2 mocykl


          Comment


            #6
            On each carb there is a rubber cap that slips on and seals the ports that are used to attach vacuum gauges for balancing the carbs.
            They are on the top of the carb at the boot side and on CV's usually have a squared off top .
            This port is a direct link to the venturi so a leak there is the same as a boot leak with air being drawn direct into the engine.
            Mikuni Viton Choke Plunger Seat Renewal.
            VITON Choke plunger seals .KAWASAKI Z1,Z900,Z650,Z1000,Z1R,SUZUKI GS1000,GSXR,RF | eBay

            Air Corrector Jets for Mikuni VM 24, 26 and 28mm carbs .
            https://www.ebay.co.uk/itm/254380193...84.m1555.l2649



            sigpic

            Comment


              #7
              Originally posted by zed1015 View Post
              On each carb there is a rubber cap that slips on and seals the ports that are used to attach vacuum gauges for balancing the carbs.
              They are on the top of the carb at the boot side and on CV's usually have a squared off top .
              This port is a direct link to the venturi so a leak there is the same as a boot leak with air being drawn direct into the engine.
              I never knew about this, I thought the intake boots have those pieces for the carb syncing.
              Ian

              1982 GS650GLZ
              1982 XS650

              Comment


                #8
                Originally posted by Redman View Post
                You say you checked for intake air leaks, I assume you mean the boots themselves are not cracked along thier body.

                Other things to concider:
                - boots old and stiff so dont seal well. boots old and stiff so the clamps have been overtightened and stretched out, and/or the boots deformed.

                - boots separating from the base flange.

                - boot o-rings old and hard. (orings up against the head)

                - (and what got me: ) O-Rings in the enricher(choke) mechanism. HAve to completely break down carbs from the rack to replace these.
                I changed the o-rings on the boots, and sprayed were they connect to the head, guess I'm gonna have to do a more in depth inspection. They didnt seem stiff but the clamps do seem a bit stretched. The carbs are a hard fit onto the boots but the clamps themselves do seem a bit worn

                Probably gonna get at it tonight.
                Ian

                1982 GS650GLZ
                1982 XS650

                Comment


                  #9
                  Plugs at idle speed, should I start messing with fuel mixture screws or is this considered okay, I dont think it is but making sure

                  Snapchat-1176956362.jpg
                  Ian

                  1982 GS650GLZ
                  1982 XS650

                  Comment


                    #10
                    Hey could you possibly tell me where the vac plugs are supposed to be, heres a picture of the carbs. Gonna replace the enrichener o rings.

                    For the choke, I noticed when I pull the rack out and let it back in I can hear air passing through

                    Snapchat-518625479.jpg
                    Last edited by timebombprod; 02-27-2021, 12:08 AM.
                    Ian

                    1982 GS650GLZ
                    1982 XS650

                    Comment


                      #11
                      Also found this and nothing is screwed into it on any of the carbs, only one hole shows threading, should I be worried about this? It's only threaded on carb 3

                      Snapchat-1854815481.jpg
                      Ian

                      1982 GS650GLZ
                      1982 XS650

                      Comment


                        #12
                        Originally posted by zed1015 View Post
                        On each carb there is a rubber cap that slips on and seals the ports that are used to attach vacuum gauges for balancing the carbs.
                        They are on the top of the carb at the boot side and on CV's usually have a squared off top .
                        This port is a direct link to the venturi so a leak there is the same as a boot leak with air being drawn direct into the engine.
                        I don't have a 650 on hand to confirm, but, from looking at the parts fiche, the sync ports are in the cylinder head and sealed with a bolt and washer
                        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
                          Originally posted by Big T View Post
                          I don't have a 650 on hand to confirm, but, from looking at the parts fiche, the sync ports are in the cylinder head and sealed with a bolt and washer
                          It's in the intake boots, one is missing a washer, gonna just replace them with o-rings for now and see if I can just find the washer around here. The carb tuner has o-rings on the fittings so it doesnt seem like a bad temporary replacement.
                          Ian

                          1982 GS650GLZ
                          1982 XS650

                          Comment


                            #14
                            Heres a video of tonight, explains what I've done and also shows the condition of my intake boots, and an idea im thinking of doing instead of buying new boots right away. Please watch!

                            Ian

                            1982 GS650GLZ
                            1982 XS650

                            Comment


                              #15
                              Originally posted by timebombprod View Post
                              Hey could you possibly tell me where the vac plugs are supposed to be, heres a picture of the carbs. Gonna replace the enrichener o rings.

                              For the choke, I noticed when I pull the rack out and let it back in I can hear air passing through.


                              [ATTACH=CONFIG]62476[/ATTACH]
                              Hi, Ian. As already confirmed , those carbs don't have the vac ports on the bodies.
                              Some do, some don't depending on model.
                              The suggestion was only to ensure it was something you hadn't missed.
                              If that thread is a blind hole it is of no concern.
                              These carbs will have been used on several different machines and various drillings and mounts may not be used depending on application.
                              As for the choke, with the bike running it's normal to hear a hiss as the plunger shuts off the passage to the venturi if you listen carefully.
                              With the new seats those plungers are guaranteed not to be passing fuel in the closed position.
                              Last edited by zed1015; 02-27-2021, 07:31 AM.
                              Mikuni Viton Choke Plunger Seat Renewal.
                              VITON Choke plunger seals .KAWASAKI Z1,Z900,Z650,Z1000,Z1R,SUZUKI GS1000,GSXR,RF | eBay

                              Air Corrector Jets for Mikuni VM 24, 26 and 28mm carbs .
                              https://www.ebay.co.uk/itm/254380193...84.m1555.l2649



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