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GS850L 1981 Idles fine and revs with choke, but bogs and dies when under throttle.

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    GS850L 1981 Idles fine and revs with choke, but bogs and dies when under throttle.

    Hi -new to GS resources, but looks like a goldmine of info. Thanks in advance to the helpful and knowledgeable folks.

    Just picked up a 1981 GS850GL, 22k miles. Beautiful cosmetic condition, but had not been run in several years. I figured it would need some attention, and have been going thru little by little. Want to get it running well before I do brakes, tires, lube, clean/shine, etc.

    When first tried to start it (with a jump of course), I turned the gas to prime and after a few mins it was leaking fuel out of the airbox. I figured it was stuck float needles, causing the carbs to overflow, and spilling into the airbox then out. So there began my carb work.

    Removed air box and carbs. Sure enough most of the float needles were gummed and stuck. Dismantled each carb one by one, dipped in cleaner all the parts and jets (not the rubber parts or diaphragm). Cleaned with carb cleaner parts that I could not dip. All orifices and jets looked nice, reassembled carbs. Did NOT dissemble the pilot air screw on engine side (the one that is sealed at factory with only a pin hole on cover) – just cleaned it out with wire and carb cleaner. Throttle plates looked synched from visual observation. After reassembly of carbs, slides went up/down nicely.

    Air cleaner element was sticky, and element holder was missing foam on top that gets squeezed between elements and top of air box. Did not fix.

    Checked gas valve, filter, lines, all looks good. Vacuum valve seems to work, and on Prime gas comes out nicely.

    Put it all back together, and no leaking gas now !!!! Jumped it and used the choke, and it started up right away ! Yeah…. Making progress. Blew lots of white smoke (figured it was clearing itself of 6 years of dust), and revved pretty good with choke on, and idles great with no choke. With no choke, when giving it any amount of throttle above idle it would just bog and lose power, even on very slow throttle advance. DARN. Looks like more work to do.

    I sprayed some carb cleaner by air boots before and after carbs, and sure enough, when sprayed by intake boots to cylinder head, the idle changed just a bit.

    Back to work.

    Pulled out air box and carbs again. Pulled off intake boots to cylinder head, and replaced the orings. Man, the old ones looked and felt like plastic – they just cracked and crumbled. Also, put new foam on air cleaner holder top surface on perimeter, and reinstalled air cleaner nice a snug into housing. Reassembled all items.

    Even replaced valve cover gasket and cam chain tensioner gasket while I was at it, since these items has been leaking slightly.

    All back together. Starts just like before, revs ok with choke. Idles fine by itself without choke. However, when rolling on throttle, it still bogs badly and wants to die. After warming it for about 3 mins, it seemed to be willing to go a little past idle with very delicate and slow throttle turning, but anything close to normal still bogs. All of this is while bike is parked on side stand in neutral. Have not ridden it yet due to flat front tire.

    Checked plugs, and they all look ok, not wet, and not heat damaged (although they are very old plugs).

    So now I am miffed. Idles fine, and runs at higher rpm with choke, but with no choke it only idles and doesn’t want to go much higher rpm without bogging badly. I am guessing this is lack of fuel, but I am not an expert and am not sure what to troubleshoot next.

    Have not checked timing or valve clearance, and have not cleaned the air filter and have not replaced the plugs. I was thinking that those items might help it run ideal once it is running just ok. Right now, just trying to get it running ok without choke.

    Any tips would be appreciated. Thanks !!!!!

    #2
    Greetings and Salutations!!

    Hi Mr. fjrider,

    The carbs have to be completely disassembled and the entire carb body dipped, sometimes up to 24 hours. Then a new O-ring kit should be installed. The mixture screw caps can be removed so that the mixture screws will come out. There is also an O-ring on the mixture screws that has to be replaced. It's all in the carb cleanup series. It's part of your "mega-welcome". Let's get started.

    I just stopped by to welcome you to the forum in my own, special way.

    If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

    Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", the Carb Rebuild Series, and the Stator Papers. Now let me roll out the welcome mat for you...

    Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

    Thanks for joining us. Keep us informed.

    Thank you for your indulgence,

    BassCliff

    Comment


      #3
      Yup, carbs need to be cleaned correctly and all the O-rings replaced. Short cuts are long cuts. Also, the air box side covers and air filter need to be sealed properly or the bike won't run right. The 850 is particularly picky about details like this.

      Good luck.
      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


        #4
        Originally posted by Nessism View Post
        Yup, carbs need to be cleaned correctly and all the O-rings replaced. Short cuts are long cuts. Also, the air box side covers and air filter need to be sealed properly or the bike won't run right. The 850 is particularly picky about details like this.

        Good luck.
        Believe this. I learned the hard way! I went with pods before learning enough about the carbs and save yourself the trouble and make that STOCK airbox tight!

        just my .02

        Comment


          #5
          Thanks to all for the advice so far. WOrked on my new tire today (success) and the front brakes (success). Before tearing into the carbs again, I sealed the air box cover (on right side of bike) with strip foam weahter sealer - it is nice and tight now. Will try to run it Tuesday night after work and see how she runs. If not any better, will plan to redo carbs (for 2nd time now).

          Just curious - for the stock air box - I have foam on top between air filter and top of box.

          I also have now foam on rigth side cover.

          Is there anywhere else that needs to be sealed up? Hard to see if any foam is "missing" cause there is none in any other place. Thanks.

          Comment


            #6
            I checked all the spark plugs - put new ones in, then checked each one to ensure spark (took off plug lead, connected to exra plug, then tried to start engine. Saw good consistent spark from each plug. As least this eliminates spark as the issue.

            I noticed that the bike sounds like it is running on less than 4 cylinders. To check my theory, after running for a few mins, I feel the exhaust pipes as the come out of the engine. Cylinders 1 and 4 are HOT, while 2 and 3 are cool to lukewarm. I pulled spark plug from #3, and see it looks a bit wet. But it sparks, so hhhmmmm.. Maybe just not getting the right fuel/air mix from the carbs.

            Still have not removed and cleaned carbs for round 2.

            Comment


              #7
              Well,you got good spark, so get those blocking caps off to get at the mixture screws- clean out passages and use new orings there. You described a stumble coming off idle and that's where clean idle circuit passages are vital- think of it as a transition zone as you open the throttle.
              1981 gs650L

              "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

              Comment


                #8
                FJ RIDER, did you ever fix this condition? I'm having the exact same problem. I just purchased a 1985 gs700es with only 6000 miles. Been sitting a long time. I took everything apart and cleaned it best I could, reassembled everything. Starts fine, idles fine, with choke revs up nicely. Choke off, and engine bogs down.

                Comment


                  #9
                  "I took everything apart and cleaned it best I could, reassembled everything. Starts fine, idles fine, with choke revs up nicely. Choke off, and engine bogs down. "

                  What exactly does "best I could" mean? full strip and dip? Do you have stock airbox (with filter element) and stock exhaust or something else?
                  1981 gs650L

                  "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

                  Comment


                    #10
                    Originally posted by fjrider View Post
                    Beautiful cosmetic condition, but had not been run in several years.

                    I turned the gas to prime and after a few mins it was leaking fuel out of the airbox.

                    Even replaced valve cover gasket and cam chain tensioner gasket while I was at it, since these items has been leaking slightly.

                    All of this is while bike is parked on side stand in neutral.
                    A few things jump out at me...

                    If you are having problems with fuel overflowing, there is likely fuel in the oil...
                    Running on the sidestand for extended periods can cause a lack of lubrication on the right side cam bearings, especially with fuel in the oil. Check the oil for fuel, change the oil if there is, and put the bike on the center stand, or at least stand it up straight when you run it.

                    And adjust the valve clearances.
                    http://img.photobucket.com/albums/v5...tatesMap-1.jpg

                    Life is too short to ride an L.

                    Comment

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