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banging my head .... update gs750

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    banging my head .... update gs750

    Help!!!! this is an update of my progress on the 81 gs 750 stumbling on its face syndrome. my other posts tell what I have done to this point. As of today I have cleaned carbs per specs here and put 45 pilots in the bike, it now starts and runs great. It will rev up to 4k sounding beautiful. It has 120 mains in it now but have not been able to get up to throttle region where the mains come into play so not sure if there correct. I have raised the needle one shim from a stock shim of one. Is this enough???? they seem so small and thin I'm not sure if one is enough. I now have a total of 2 shim washers on the needles. When I take it out onto the street it stumbles at 4k, just can't get anything out of it at that point. Whats going on here????? due to the throttle position, I'm around a 1/4 to 1/2 throttle when it acts up and this should be in the needle circut, am I correct????

    I raised the needle hight because it was stumbling in the same place prior to the current mods and was advised that it was in the needle circut needing more fuel, is this correct???

    some recape: the bike has pods and a VH 4/1. plugs look lean right now. all are firing.

    The bike has gone from not starting and running when I first got it (had 112.5 mains and 42.5 pilots), to being to rich and fouling the plugs with(122.5 mains and 60 pilots) to 55 pilots and still hard to start, to whats in her now. 120 mains and 45 pilots with needles having 2 shims.

    can a bad petcock be causing some of this?? fuel seems to be flowing just fine.

    Its just falling flat on its face at around the 4k mark. 1/4 -- 1/2 throttle area. Thanks for any and all imput.

    #2
    Get a Dynojet stage 3 kit. Run it with a 45 pilot jet.
    What size pilot air jet do have installed? That's the jet on the filter side.
    1983 GS 1100E w/ 1230 kit, .340 lift Web Cams, Ape heavy duty valve springs, 83 1100 head with 1.5mm oversized SS intake valves, 1150 crank, Vance and Hines 1150 SuperHub, Star Racing high volume oil pump gears, 36mm carebs Dynojet stage 3 jet kit, Posplayr's SSPB, Progressive rear shocks and fork springs, Dyna 2000, Dynatek green coils and Vance & Hines 4-1 exhaust.
    1985 GS1150ES stock with 85 Red E bodywork.

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      #3
      thanks for the reply. looks like a 170 air jet. does that sound right???

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        #4
        Yup, that's stock.
        1983 GS 1100E w/ 1230 kit, .340 lift Web Cams, Ape heavy duty valve springs, 83 1100 head with 1.5mm oversized SS intake valves, 1150 crank, Vance and Hines 1150 SuperHub, Star Racing high volume oil pump gears, 36mm carebs Dynojet stage 3 jet kit, Posplayr's SSPB, Progressive rear shocks and fork springs, Dyna 2000, Dynatek green coils and Vance & Hines 4-1 exhaust.
        1985 GS1150ES stock with 85 Red E bodywork.

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          #5
          should I change it???

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            #6
            Originally posted by shack426 View Post
            should I change it???
            No. The problem you're having is during the needle ciruit. The Dynojet adjustable needle will take of this. Also drilling the slides will raise the slides quicker and the combo will take care of the stumble.
            1983 GS 1100E w/ 1230 kit, .340 lift Web Cams, Ape heavy duty valve springs, 83 1100 head with 1.5mm oversized SS intake valves, 1150 crank, Vance and Hines 1150 SuperHub, Star Racing high volume oil pump gears, 36mm carebs Dynojet stage 3 jet kit, Posplayr's SSPB, Progressive rear shocks and fork springs, Dyna 2000, Dynatek green coils and Vance & Hines 4-1 exhaust.
            1985 GS1150ES stock with 85 Red E bodywork.

            Comment


              #7
              Hey Chef, thanks for all the help. I apprecitate it.

              Comment


                #8
                Originally posted by shack426 View Post
                Hey Chef, thanks for all the help. I apprecitate it.
                No problem. Are you going to get a Dynojet kit?
                1983 GS 1100E w/ 1230 kit, .340 lift Web Cams, Ape heavy duty valve springs, 83 1100 head with 1.5mm oversized SS intake valves, 1150 crank, Vance and Hines 1150 SuperHub, Star Racing high volume oil pump gears, 36mm carebs Dynojet stage 3 jet kit, Posplayr's SSPB, Progressive rear shocks and fork springs, Dyna 2000, Dynatek green coils and Vance & Hines 4-1 exhaust.
                1985 GS1150ES stock with 85 Red E bodywork.

                Comment


                  #9
                  ASAP, looks that'll solve the problem. I'll try and post a picture, its got a bobber look to the bike, the PO did some mods to make it look different. Lowered, single sportster style seat, back seat and frame been cut off as well as the rear fender. Once I get it running I need to get some rear trun signals, but I would like to find somthing small, very small that has that wild custom look. Talk to you soon....................Shack426.

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