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Jetting questions w/ new 4-1 exhaust

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    Jetting questions w/ new 4-1 exhaust

    I got my new V&H 4-1 today and installed it. Easier than I thought, only took a few hours. Pipe cost over 1/2 of what the bike cost
    I wasn't prepared for how loud it would be. First off, the bike starts and idles better and comes off choke way sooner, which was unexpected. Took the bike for a ride, and it has hesitation around 4-5K rpm, seems to have more on top but its hard to tell from seat of the pants.
    The pipe came with a sheet of paper with jetting recommendations, it says to remove stock airbox lid, increase main jet to 130 and use a 42.5 pilot jet. I am not sure what the pilot jet does. Will these changes remove the hesitation? Stock main is supposed to be 112.5 and pilot jet is already 45 depending on what manual you read I would think that the needle should be richened and main increased.
    Thanks
    Gear.




    #2
    yes, richen the needles first
    that's all you may need to do (as you have a canadian model)
    GS850GT

    Comment


      #3
      Originally posted by gearhead13 View Post
      First off, the bike starts and idles better and comes off choke way sooner, which was unexpected
      the original pipes are double skinned and more easily disipate the heat from the engine so it takes longer to warm up

      the faster flow of gases in the 4-1 system leans the fuel/air ratio accelerating the warm up of the engine
      GS850GT

      Comment


        #4
        thanks Psyguy.
        Q: is it possible to pull the slides out with the carbs still on?
        I am going to be pulling the carbs and cleaning them, but I am waiting for the o-ring kit from Robert Barr.

        Comment


          #5
          not 100% sure for your exact model, but...

          yes, most likely possible to pull out the slides with the carbs still on
          watch the diaphragms dont get damaged though
          GS850GT

          Comment


            #6
            Originally posted by gearhead13 View Post
            Q: is it possible to pull the slides out with the carbs still on?
            I am going to be pulling the carbs and cleaning them, but I am waiting for the o-ring kit from Robert Barr.
            A: Yes, it is possible to pull the slides with the carbs still on the bike. But ... (Seems therre's always a butt in there somewhere.)

            I have occasionally had problems getting the slides back in, trying to get the needle back down into the jet.

            Since the instructions say you need to change the main jet, too, why not just do it all at once when the carbs are already off the bike?

            Oh, and if you are waiting for o-rings from Robert, you won't be waiting long. I have always had good, quick service from him.

            .
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              #7
              Do you think a 130 main is a good place to start?
              I have to get them ordered in as no one around here carries any kind of decent selection.
              Last edited by Guest; 07-24-2008, 07:21 PM.

              Comment


                #8
                If the stock pilot jet is 45 I'd bump that up to 47.5
                If the stock main jet is 112.5 I'd bump that up to 122.5 to 120
                You'll also have to raise the needle by replacing the stock plastic needle spacer with washers. To raise the needle you will need more needle sticking out of the end of the spacers. Do a search. I've written about how many washers=a spacer but I can't remember.
                I'd personally go with a Dynojet stage 1.
                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
                  non-usa models often have bigger jets from the factory
                  they also have needles that have groves so its easy to adjust them

                  i would try this first before spending money ordering any new jets

                  for comparison, i run 115 main jet and 42.5 pilot jet (stock setting) with 4-1 exhaust (on an 850)
                  Last edited by psyguy; 07-24-2008, 10:40 PM.
                  GS850GT

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                    #10
                    My bad. Canadian. You probably already have a notched needle.
                    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


                      #11
                      Ya, they are notched, but they were on the second to last notch already. I took it for a ride today and it overheated within 20 minutes
                      I am waiting for main jets. I moved the clip to full rich and added a little spacer as well. Goin for a ride now to see what it does now

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                        #12
                        I was able to pull the slides out with the carbs still on, no problem.
                        Runs better. Maybe a tad rich.
                        Sounds like a can of metal nuts at idle, need to deal with that next.

                        Comment


                          #13
                          Are you lowering the clip to raise the needle to richen??
                          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


                            #14
                            Originally posted by chef1366 View Post
                            Are you lowering the clip to raise the needle to richen??
                            yes. Those needles were very straight hardly any taper at all

                            Comment


                              #15
                              That's how all my stock needles have looked. I always switch to Dynojet.
                              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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