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Hesitation between 2500 and 3500 RPM

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    Hesitation between 2500 and 3500 RPM

    My 82 GS850G stumbles at low RPM at less than a 1/4 throttle. If I twist the throttle more it takes off. The engine previously wouldn't idle and backfired, wasn't rideable. I took the carbs off cleaned them thoroughly and now it starts well, idles fine and cranks up to redline fast. The problem is at low throttle. I adjusted the valves and that didn't help. I'm the original owner with 22,000 miles and has always been garaged. Gas tank is clean. Any suggestions?

    #2
    Have you vacuum synched the carbs? Just throwing it out there.
    Jordan

    1977 Suzuki GS750 (My first bike)
    2000 Kawasaki ZRX1100
    1973 BMW R75/5

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      #3
      Original owner- that's impressive! So just how did you "thoroughly" clean your carbs? Sounds like lack of mixture as throttle plates start to open past their idle sweet spot. Note the tiny holds in carb throat that aid the transition to higher speed/loads.image.jpg
      1981 gs650L

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

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        #4
        Also, what is the state of the airbox, filter, and the rubber bits on either end of the carbs?
        Dogma
        --
        O LORD, be gracious to me; heal me, for I have sinned against you! - David

        Skeptical scrutiny is the means, in both science and religion, by which deep insights can be winnowed from deep nonsense. - Carl Sagan

        --
        '80 GS850 GLT
        '80 GS1000 GT
        '01 ZRX1200R

        How to get a "What's New" feed without the Vortex, and without permanently quitting the Vortex

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          #5
          Try adding a little choke as your rolling along..if it gets better that points tom it running lean. If it gets worse that points to its too rich. At least this will give some sort of quick initial impression.
          MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
          1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

          NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


          I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

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            #6
            I took carbs off and removed everything but the floats. I used 2 cans of carb cleaner along with compressed air. I soaked the jets overnight and made sure the jets were cleaned out by putting a pin through all the holes. I adjusted the floats to factory spec. The air box was removed and completely cleaned out. If I add a little choke the hesitation stops so it must be running lean. The only thing I can think to do now is to buy new jets. The bike is totally stock so I wouldn't think changing jet size is necessary but I don't know that for sure. I'm open for suggestions.

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              #7
              Well let me tell you whats wrong.....In your description of your "cleaning" you never mentioned dipping the carb bodies and giving them the same air and carb spray attention you gave the jets. Get Some Berrymans dip and take the basket out. You can do 2 bodies at a time this way. Go for the full 24 soaking and clean the bodies and youll have the carbs done right.
              Last edited by chuck hahn; 04-23-2017, 10:32 AM.
              MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
              1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

              NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


              I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

              Comment


                #8



                EDIT..get new rubber plugs for the pilot jets. The old ones have taken a set and may or may not seal. If they dont youll be running rich and never get it right till theses plugs are replaced. And no they cant be sealed with RTV. Yes i have rebuilt customers carbs and actually saw they tried to fix leaky plugs this way..which led to the RTV breaking down and getting sucked into the pilots..thus stopping the bike cold.
                Last edited by chuck hahn; 04-23-2017, 10:36 AM.
                MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
                1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

                NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


                I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

                Comment


                  #9
                  I did replace the rubber plugs but I did not soak the carbs overnight but I will do that next.

                  Comment


                    #10
                    see the link I posted too. Clean jets do nothing if the passages they feed arent clear too.
                    MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
                    1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

                    NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


                    I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

                    Comment


                      #11
                      Can I leave the carbs mounted on the frame when I dip 2 at a time? I assume that's what you meant. Should I replace the rubber boots between the carbs and the engine? That would also make it run lean if they are not sealing properly.

                      Comment


                        #12
                        No..fully disassemble the rack. No rubber or plastic bits in the dip. Be sure to remove the top mixture screws and remove the small metal washer and orings that go on the needles. Account for all 4 washers and orings and put the. and the springs in a zip loc baggie so they dont get lost. When reassembling each carb, set the mixture screws at 2 1/2 out for initial starting.

                        IF the mixture screws have the metal caps from the factory over them, then GENTLY drill through the caps and screw in a deck screw in the hole. ank the caps out with some vice grips.

                        Also note that should the caps be on the screws that means they have been set by Suzuki...which gives you the advantage of recording what each one is set at. Start with the left carb (#1 ) and carefully screw the screw in till it stops and dont force it. Note how many turns in it takes and repeat on the other 3 carbs. I make a mark on top of the hole inline with the slot for referrance. Then start turning the screw. By a "turn" I mean that 1 full 360 degree turn of the screw equals 1 turn. Write the turns down in relation to what carb its in and set them the same when you reinstall the mixture screws after the dipping.
                        MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
                        1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

                        NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


                        I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

                        Comment


                          #13
                          The metal caps are on the mixture screws and I have drilled them out before on another vehicle so no problem. I will follow your instructions and let you know how it worked out. thanks for your help!

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                            #14
                            It probably has broken O Rings on the carb boot to head connection. Carb boots tor those are expensive, in case fairly likely case that it needs those too.
                            sigpic Too old, too many bikes, too many cars, too many things

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                              #15
                              I will order new carb boots and o rings. They are original and feel pretty hard.

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