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    Bike dies if any throttle is given.

    Hello all I have just found this board and am hoping you can help me. I am trying to get my 1981 GS650g running. It has been sitting around for about 3 years and it wasn't stored properly still had gas in it. I removed and cleaned the tank, replaced the air filter, and check the spark plugs. After putting fresh gas and a charged battery in I started it. It started almost immediately with full choke and I can get it to idle as long as I keep the choke on but the bike dies if the choke is off. Also the bike will die immediately if I give it any throttle at all. This happens if the choke is on or not. Any help you can give would be muck appreciated.

    #2
    Those carbs are going to have to come off the bike and be cleaned. The choke circuit works seperately on the carbs from the idle and main circuits. My guess is that the pilot jets are plugged up. Go to the main page on this site and look at the Carb cleanup series. Nice step by step on how to clean up these carbs.

    Dan

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      #3
      You need to clean the carbs. Sounds like your idle jets are clogged up. The quick fix, that may, or may not work, is too take your carbs off, pop off the bowls, and take out the idle jets. They are usually under a rubber cap, next to the main jet. It takes a small flat head screwdriver. Take a wire from a wire brush, or the like, and poke it thru the jet to clean it out. Do the same for the main jets it they're clogged.

      If that doesn't work, you have some other places clogged up in the body, and you'll have to disassemble everything, and dip em in carb cleaner. If you don't want to do it again, do this first. You'll need some o-rings.

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        #4
        Sounds a lot like an intake leak to me on top of the carbs likely needing cleaning. My guess is that this is why it'll run on full choke (rich enough) but dies without choke or with throttle. (Too lean)

        I'm not sure off the top of my head if your bike has intake boots with a flange and o-rings or just a pipe between the head and carbs but whatever you have I'd check for leaks. If you have o-rings you'll want to replace them while the carbs are off whether they leak or not, saves pulling the carbs again later for a few $ in parts.

        /\/\ac

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          #5
          Usually what happens is the idle jets get clogged, because they're the smallest jet. With the idle jets clogged, it will start up on full choke, albeit maybe a bit harder then it should. The "choke" causes the slide to raise up behind the throttle plate, allowing more fuel to come thru, but the throttle plate remains closed, so it limits the air, this combo gives you a rich "choked" condition. When you shut off the choke, it runs primarily off the idle jet, so if it's clogged, and the choke isn't giving it fuel thru the needle jet, it's going to die. The same premise goes for opening the throttle. By opening the throttle, it negates the choke, the slide then moves normally in accordance to the throttle plate position. The slide though is calibrated to deliver the proper mixture in addition to the amount of fuel the idle jet is providing. If it's clogged, it runs really lean, bogs, and dies.

          That said, replacing the o-rings isn't a bad idea, it's cheap, so why not. I've found that o-ring leaks will cause nagging problems, the bike will run, but not quite right. An easy test is to spray some WD40 around the boots while she's running, if rpms increase, you have a leak.

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            #6
            Thanks for all the replies. I will look in to getting the carbs cleaned and replacing the O -rings.

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              #7
              One other thing. Will the carbs have to be synchronized after they are removed and cleaned?

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                #8
                Originally posted by Darknar
                Hello all I have just found this board and am hoping you can help me. I am trying to get my 1981 GS650g running. It has been sitting around for about 3 years and it wasn't stored properly still had gas in it. I removed and cleaned the tank, replaced the air filter, and check the spark plugs. After putting fresh gas and a charged battery in I started it. It started almost immediately with full choke and I can get it to idle as long as I keep the choke on but the bike dies if the choke is off. Also the bike will die immediately if I give it any throttle at all. This happens if the choke is on or not. Any help you can give would be muck appreciated.
                You have the imfamous "plugged pilot jet(s)".

                Comment


                  #9
                  Yes, but if you don't have the tool, you can get it pretty close using a drill bit as a spacer, adjust it so that each throttle plate has the same about of space between it, and the bottom of the venturi.

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                    #10
                    Thanks agian for the help.

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