Calling all carb gurus

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  • Jason the terminator
    • Feb 2026

    #1

    Calling all carb gurus

    It started out trying to get my carbs jetted properly. I ordered a Dynojet kit, K&N pods and a Marving exhaust to replace the V&H 4to1 (so I would have a few more inches of ground clearance).

    The PO had installed the V&H and jetted it by putting a 160 pilot air jet, 47.5 pilot jet, 125 mains. It would pop on decel indicating a lean condition.

    I installed the Dynajet kit per instructions. Drilled the slides, 138 main, needle 3rd notch down, floats 22.4mm, 2 1/2 turns out on mixture screw, 160 pilot air jets cause I did not have the 170s. A bench sync was done also. I tried to get it to run with no luck. Checked the spark and it was week so I did a coil relay mod. Still could not get it to run properly.

    Got a hold of Rustybronco to ask some questions and he offered to come over and give me a hand. After many hours trying to get it running he said I need to get the stock air pilot jets(170) and it was still blowing the spark out. So I investigated and bad signal generator and the ignitor was not testing good per manual.

    Now we are into riding season so I was not going to mess around and try and figure out a 30 electrical system. I just order the 170 pilot air jets and a Dyna 2000 kit. When I received them I installed figuring that my problems were solved but they are far from it.

    The pilot system is to rich. At 2 turns on the mixture screws at idle it will fowl the plugs in about 30 sec. After some phone calls with Rapidray and Rustybronco today here is where I am at. With 1 turn out, no pod filters and wet float height at 7.5mm it will idle and rev but has a flat spot at 2-5000rpm. It still seems on the rich side still.

    The bike only has 6k original miles on it and all the parts that I listed were purchased new. The only thing that I am wondering about is that it looks like the valve cover was removed and wonder if the PO degreed the cams. If so could this add to my issues?
  • Big T
    Forum LongTimer
    Past Site Supporter
    Super Site Supporter
    • Mar 2005
    • 12392
    • West Slope, OR

    #2
    The flat spot shows you have a problem other than the main jet

    Where do you have the needle set at?

    If the cams were off, you would have poor performance. Pop off the valve cover and check the alignment
    1978 GS 1000 (since new)
    1979 GS 1000 (The Fridge, superbike replica project)
    1978 GS 1000 (parts)
    1981 GS 850 (anyone want a project?)
    1981 GPZ 550 (backroad screamer)
    1970 450 Mk IIID (THUMP!)
    2007 DRz 400S
    1999 ATK 490ES
    1994 DR 350SES

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    • Jason the terminator

      #3
      Originally posted by Big T
      The flat spot shows you have a problem other than the main jet

      Where do you have the needle set at?

      If the cams were off, you would have poor performance. Pop off the valve cover and check the alignment
      Needles are third notch from the top.

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      • Jason the terminator

        #4
        One more little bit of info I am running Premium fuel. I don't think this should really matter but who knows.

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        • rustybronco
          Forum LongTimer
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          • Jul 2005
          • 14961
          • Marysville, Michigan

          #5
          Jason, Premium fuel won't matter.

          Did you get a chance to drill a drain screw yet. if not I can drill one out sometime today.
          De-stinking Penelope http://thegsresources.com/_forum/sho...d.php?t=179245

          http://www.thegsresources.com/_forum...35#post1625535

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          • Jason the terminator

            #6
            Originally posted by rustybronco
            Jason, Premium fuel won't matter.

            Did you get a chance to drill a drain screw yet. if not I can drill one out sometime today.
            Couldn't find the right size, 6 mm but fine thread. I did get a piece of tubing that is about the same size as the screw. I got it in the hole and it dripped some but not horrible. Float height was at 7mm. That would make it a bit on the lean side correct?

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            • rustybronco
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              • Jul 2005
              • 14961
              • Marysville, Michigan

              #7
              I had to look up the spec. my 850 book said 4.5~5.5mm. 7mm would make it run lean.

              how many carbs have you checked and were (was) the bowl(s) full?
              De-stinking Penelope http://thegsresources.com/_forum/sho...d.php?t=179245

              http://www.thegsresources.com/_forum...35#post1625535

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              • Jason the terminator

                #8
                Yeah it is 4-5mm. I only check the one as it was late. I'm going to check the others later today.

                Well with the bowls lean and pods off it seems like a step in the right direction. It would actually run like this. I pulled the plugs after it ran for a few min. They were full of soot but not wet like they have been all the other times when it would die after 30 sec of running.

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                • Jason the terminator

                  #9
                  Didn't get a chance to pull the valve cover today got busy doing other things. I am really in need of any advice I could get.

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                  • rustybronco
                    Forum LongTimer
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                    • Jul 2005
                    • 14961
                    • Marysville, Michigan

                    #10
                    I'll be stopping on by after I get off work.
                    De-stinking Penelope http://thegsresources.com/_forum/sho...d.php?t=179245

                    http://www.thegsresources.com/_forum...35#post1625535

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                    • Jason the terminator

                      #11
                      Originally posted by rustybronco
                      I'll be stopping on by after I get off work.
                      Thanks, I appreciate it.

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                      • Jason the terminator

                        #12
                        I just got off the phone with Dynojet and the tech was not very helpful. He said "well I don't know.... you got me". I know wait for a return phone call for more words of wisdom from him. I don't have a whole lot of faith it will get sort with his help.

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                        • rustybronco
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                          • Jul 2005
                          • 14961
                          • Marysville, Michigan

                          #13
                          Jason, this is what worked for TCK.


                          needles forth clip from the bottom...
                          and my thoughts as well.
                          Last edited by rustybronco; 07-11-2011, 02:33 PM.
                          De-stinking Penelope http://thegsresources.com/_forum/sho...d.php?t=179245

                          http://www.thegsresources.com/_forum...35#post1625535

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                          • Jason the terminator

                            #14
                            Ok I checked the valves and all are at .004 which is spec. Stopped at the local bike shop and talked to them. They asked a bout the throttle cable, choke, slides hanging up, valve clearance which are all fine. I picked up some 40 pilot jets and they didn't have 42.5 or any pilot air jets. I am going to drop the needle one notch and see where we are at.

                            On another note still no word from Dynojet 5 hours later. Guess they don't care to help once they got your money. If I ever purchase another jet kit it will be a Factorypro and Dynojet can go fly a kite.

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