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1983 GS550ES Fuel Delivery Issue

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    #16
    Originally posted by joeman001 View Post
    OK.

    So I was completely wrong and the fuel petcock is working totally fine. The float bowls were full of gas still which was stopping the fuel from flowing to the carbs. I also took a look at the carb and the guy before me drilled out the air/fuel mixture plugs and turned all the screws to like 3 to 3.5 turns when its supposed to be 2.5. I turned them all back to 2.5 and now the bike is starting (although i had a lot of trouble getting it to start but now it starts fine) but even with the choke on/off it still rockets up the in the RPMS. I tried adjusting the idle screw as low as it would go and still no luck. Instead of idling at 5-5.5k RPM though it fluctuates between 3.5 to 4.25 RPM now. Also it no longer starts out at around 1-2k rpm idle its just straight to 4K rpm with whether its on choke or no choke. Do you guys think I should turn the screw more to around 2 turns instead? I don't feel like that's going to make a massive difference though. Honestly I'm running out of ideas and the bike when I first got it had 175PSI compression on all cylinders and I am getting really worried that the engine is going to be destroyed by the time i get this thing fixed since its constantly running lean. I've heard horror stories about valves being eaten alive by lean conditions. Anyways thanks for all the help, if any of you in the Cincinnati area know somewhere or one who knows these bikes well enough to work on them please let me know because I might have to take this in to a dealer and pay an exorbitant amount of money to have this fixed.

    Thanks, Joe
    With the engine running if you twist open the throttle grip is their an immediate response?
    There should be a measurable free play at the grip.
    Also the choke cable is apt to get sticky. If lubed and in good order you can verify the plungers are working freely by carefully removing them from the carb body. Actuate choke lever both sides should move freely and equally.
    You are not likely to have a problem twist grip side but may have inadvertently. Reattached the card end of the cable wrong.

    I dimly recall having the carb end off and that resulting in the cable getting off its proper position grip end of things.

    So check the mechanics of choke and throttle and we can move on.

    A Previous owner may have messed with carb internals. But that is another issue.
    1983 GS 550 LD
    2009 BMW K1300s

    Comment


      #17
      Hi again,

      So i checked the throttle response and its pretty much immediately shoots up in the rpms but has a hard time coming back down. There seems to be a good amount of slack on the throttle cable and i can rotate the grip about 5 degrees before the throttle grip starts to catch and open the throttle on the carbs. I checked the choke cables and they both move in and out freely and seem to fully extend. I made sure that they were correctly seated and i put a drop of teflon oil on each to make sure they move really well in the choke slides on the carbs. I turned the air/fuel screws down to 1 turn out and it actually didnt immediately rocket up to 5k Rpms and stayed relatively low in the RPMS (close to OEM idle speeds) and I could even rev the engine and the rpms would come down like you would expect them too. However after about 5 minutes of running the rpms kept going up and eventually after i revved it again the rpms shot up and stayed there like usual. I took the boots off and i ran the bike to look at the slides inside the carbs to make sure the diaphragm isn't holding them up and they were working perfectly. I absolutely doused all the seals in WD40 to see if there was a vacuum leak and i got no white smoke or drop in RPMS. Everything ive checked so far seems to be perfect but something causes the bike to rocket up in the RPMs after it warms up and I dont know what could cause that. Anyways let me know what I should check for next going forward, i appreciate your help.

      Thanks,
      Joe

      Comment


        #18
        Sounds like an air leak. Spraying stuff on the carbs doesn't always find leaks. Maybe one of the carb boots are cracked? The RH side one is available (not cheap) but the LS side seems discontinued. Not sure what to suggest.
        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


          #19
          Two thoughts
          Replace the vacuum line between the petcock and carb #2. It is on carb #2, right?
          Did you replace the O rings in the carbs?
          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


            #20
            Yes vacuum line goes to the right side carb. Could try replacing it but it seems to be in really good shape but i could give it a try. Yes i replaced the O-Rings with genuine Suzuki Viton O-Rings so it should be perfect. Not sure what to thing maybe the pilot circuit is gummed up even though the carbs were very clean? When i turned the air/fuel screw one turn out it seemed to be hunting for an idle the whole time and then once the engine was really hot it started to rev high again. Not sure what to think on this anymore.

            Thanks for the help,
            Joe

            Comment


              #21
              Hi,

              I did order the right side intake just in case but comparing it to the one on there its pretty much in the exact same condition. I also had the air box completely off the carbs to make sure the slides were not being held up by the diaphragm and it ran significantly worse with them off so maybe im wrong here but if there was vacuum leak that bad wouldnt it run about the same? Im just throwing darts at a board here let me know if you have any other suggestions.

              Thanks for the help,
              Joe

              Comment


                #22
                Originally posted by joeman001 View Post
                Hi again,

                So i checked the throttle response and its pretty much immediately shoots up in the rpms but has a hard time coming back down. There seems to be a good amount of slack on the throttle cable and i can rotate the grip about 5 degrees before the throttle grip starts to catch and open the throttle on the carbs. I checked the choke cables and they both move in and out freely and seem to fully extend. I made sure that they were correctly seated and i put a drop of teflon oil on each to make sure they move really well in the choke slides on the carbs. I turned the air/fuel screws down to 1 turn out and it actually didnt immediately rocket up to 5k Rpms and stayed relatively low in the RPMS (close to OEM idle speeds) and I could even rev the engine and the rpms would come down like you would expect them too. However after about 5 minutes of running the rpms kept going up and eventually after i revved it again the rpms shot up and stayed there like usual. I took the boots off and i ran the bike to look at the slides inside the carbs to make sure the diaphragm isn't holding them up and they were working perfectly. I absolutely doused all the seals in WD40 to see if there was a vacuum leak and i got no white smoke or drop in RPMS. Everything ive checked so far seems to be perfect but something causes the bike to rocket up in the RPMs after it warms up and I dont know what could cause that. Anyways let me know what I should check for next going forward, i appreciate your help.

                Thanks,
                Joe
                If what you've written is true and the engine runs strong and smooth then sadly you have an air leak.
                You said you changed the intake o rings? What source did you use?
                Did you replace number 23in this fiche? I got mine from member Robert barr and it fixed the exact symptoms on the same powerplant for me.
                the difference old to new is shocking in terms of dimension and flexibility.
                Last edited by Cipher; 05-02-2021, 05:40 PM.
                1983 GS 550 LD
                2009 BMW K1300s

                Comment


                  #23
                  Hi,

                  Yes i replaced the part #23 o-rings with the genuine suzuki viton o-rings. My dad bought the O-Rings and i think he got them from Suzuki Parts Monster or something? They seemed very pliable when i put them in and i put a drop of oil on all of them when I put them in. They came in a sealed bag with the Suzuki sticker than comes on all their OEM parts. I might try and use a propane torch without lighting it and run it around the seals and everything to see if the engine speed changes to see if I cant find a leak somewhere. Let me know what you think.

                  Thanks,
                  Joe
                  Last edited by joeman001; 05-02-2021, 07:11 PM. Reason: added more info

                  Comment


                    #24
                    Update:

                    I have no clue what else to try at this point. I ran a propane torch around every single seal and the carbs to make sure its not leaking from anywhere. It isnt leaking at all because nothing about the idle changed. Its almost like its running completely on the main jets when its warmed up. I thought that maybe it was because the pilot circuit wasnt sucking any air and when i took the airbox off to see if those small holes were pulling a vacuum they werent. I sprayed a ton of seafoam carb cleaner into these holes and now they create some suction but it still rockets up to 5500 rpm. It idles significantly better at 1 turn out than it does at 2 turns out even though my problem should be caused by lean conditions by having it 1 turn out should make it super lean and it runs better that way. The only possible thing I could think of is that since the pilot jets in the carbs are size 40 instead of 35 is that when i lean it out to 1 it runs better because it is getting less fuel which would simulate the conditions of the 35 size jet. Considering ripping the carbs apart and soaking all the metal in one of those Berrymans paint cans full of carb cleaner to try and seriously unblock all the passages. If anyone has any other suggestions let me know. Otherwise im going to just keep monkeying with it until i unfortunately have to take it to a shop or sell it. Thanks for all the suggestions again guys.

                    Best,
                    Joe

                    Comment


                      #25
                      Originally posted by joeman001 View Post
                      (...) Considering ripping the carbs apart and soaking all the metal in one of those Berrymans paint cans full of carb cleaner to try and seriously unblock all the passages. (...)
                      So when you wrote in Post #1 that you've cleaned the carbs; you didn't mean you had them apart? That would be Newbie Mistake 1B.

                      Could've saved a whole lotta time.
                      #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


                        #26
                        Originally posted by roeme View Post
                        So when you wrote in Post #1 that you've cleaned the carbs; you didn't mean you had them apart? That would be Newbie Mistake 1B.

                        Could've saved a whole lotta time.
                        I'm surprised this didn't come up earlier in the thread. It's usually point #1 in cases where bikes have come from a previous owner (PO). You'd think that the carbs would be pristine, not having been run in that long, but only if they were empty of gas before it sat.

                        It's a great idea to run the carbs dry before storage.
                        '83 GS650G
                        '83 GS550es (didn't like the colours in the 80's, but they've grown on me)

                        Comment


                          #27
                          Originally posted by joeman001 View Post
                          Y

                          will keep trying on this one. I dread the thought of sending it into the local dealer for a $125 per hour service charge

                          -joe
                          Don't, just don't...most shops do not have the time or inclination to put the required work into your bike.
                          '83 GS650G
                          '83 GS550es (didn't like the colours in the 80's, but they've grown on me)

                          Comment


                            #28
                            Hi,

                            I have had the float bowls off and took out all the jets to clean them and the passage ways. I didn’t do a complete teardown because I was afraid of ruining a part. I had the hats off too to check the diaphragms and needles. Everything was super clean but maybe I didn’t go far enough.

                            -joe

                            Comment


                              #29
                              Originally posted by joeman001 View Post
                              Hi,

                              I have had the float bowls off and took out all the jets to clean them and the passage ways. I didn’t do a complete teardown because I was afraid of ruining a part. I had the hats off too to check the diaphragms and needles. Everything was super clean but maybe I didn’t go far enough.

                              -joe
                              Ignore the smug school marms. If the engine runs strong and steady its not dirt as roo.t cause.
                              Especially if it starts easily.

                              This carb has no real adjustability except swapping of main jets. The spec is clearly viewable so if they're stock most likely everything else is

                              Check spark plugs black white or tan?
                              You do of course have the intake fully assembled. Airbox on, filter installed?
                              Last edited by Cipher; 05-04-2021, 09:38 PM.
                              1983 GS 550 LD
                              2009 BMW K1300s

                              Comment


                                #30
                                Hi Cipher,

                                Just wanted to drop you a quick update. I turned the air fuel screw down to a half turn out and the bike no longer is ready to rev to the moon. It’s drivable. Obviously I can’t leave it like that so I ordered the size 35 jets to replace the size 40 pilots that are in there now. I don’t know why 40 pilots are in there but the manual says 35 so I’m going to hope that replacing it will fix my problem. I will be back with another update once they are installed but I think I’ve found the problem and it was caused by the engine running way too rich not lean because it only revved high when I got hot. Thanks for the help again.

                                best, Joe G

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