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78 gs750 with vance and hines jetting ?'s

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    78 gs750 with vance and hines jetting ?'s

    i have a 78 gs750e with stock airbox a vance and hines 4 into1 exhaust,i live at sea level in seattle what size main jets should i be running?the bike starts and runs have even been able to ride it a short distance but it only likes to rev out if you roll the throttle open slowly.open it slow arnd it revs fine but open it normal and it bogs.i cleaned the carbs and it has 100 main jets in it.should it be bigger since it has a aftermmarket exhaust.the carbs are clean so are the points. so it seems like its not getting enuf fuel

    #2
    Originally posted by paradisejaps View Post
    i have a 78 gs750e with stock airbox a vance and hines 4 into1 exhaust,i live at sea level in seattle what size main jets should i be running?
    105 mains for sure
    John 3:16

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      #3
      IMO I think you are looking at the wrong carb circuit. I would first determine what needles are installed ( are they stock) and then determine the needle clip position. I would adjust the fuel air screw then the air screw to achieve high idle on each cylinder. A carb synch is in order as well. The main jet size as GabrielGoes states should be a 105, four sizes larger than stock (IIRC the 750 uses a Main # 95) The point is the main circuit is not affecting your bogging symptom
      Steve

      1979 GS1000E (45 Yrs), 1981 GPz550 (11 Yrs)

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        #4
        I don't know why I continue to post the "official" Vance and Hines recommended jetting because everyone has their own opinion and you will hear them all. Okay with that said, for a GS750 2V model: Increase the main jet to a 115. Pilot jet should be increased to a 17.5. The needle may need to be raised one notch. (lower the clip).
        I have used the V & H jetting instructions on a number of bikes and found it to be very close if not dead on.

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