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Hesitation on 99' GP1200

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  • Hesitation on 99' GP1200

    I have seen suggestions and similar problems in many forums, but no solutions to a hesitation from idle when going from idle to WOT. Sometimes the ski even dies and takes a while with full choke to get started (seems like lean to me). I have read anything from lean low speed to rich low speed to pop-off pressure to high or too low.
    I am going out today to check if it is a hollow lean condition or gurggle rich condition.
    This ski is completely stock with around 70hrs on it.
    Before I tear down the carbs and intake I sure would like to hear any solutions that people have found.

    Thanks

  • #2
    Re: Hesitation on 99' GP1200

    No one can suggest a solution until you can accurately describe the problem. All those causes are possible, but we need to know EXACTLY what it's doing.
    SBT Tech Support is here to help with your problems.
    We try to answer each question quickly and accurately.
    Please do not use Private Messaging for Tech Support, use the forums.

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    • #3
      Re: Hesitation on 99' GP1200

      Just got back from a lake test. Here is what happened.

      I started with low speed screws at factory settings ...#1 - 1 1/4, #2 - 1 1/4, #3 - 1 1/8 turns out.
      I let it idle for about 30 sec. then gunned it. Just died. no gurggle, no nothin, just died. Re-started it and eased into the throttle and ran it WOT for about 60 sec. Slowed down to idle for 30 sec., gunned it. The ski hesitated (sounds like it starved to me) for a sec then took off. Did this two more times with the same result.
      I then went out on the low speed screws 1/4 turn. With the same tests from idle the ski gurggles a little then hits the powerband and takes off. Turned the screws out another 1/8 and gurggle time increased. I went back in on the screws until there is a slight gurggle. If I turn the screws in any more the motor starves for a second then takes off with no gurggle. I spent about 3 hours testing and turning in and out ever so slightly on the low speed screws only and the best I could get is a slight gurggle then it takes off.
      Is this normal on the stock 1200?
      I have a 650 kawi and I can adjust the low speed to where it just takes off with no hesitation no matter how long it idles, hot or cold. ( Only one carb to deal with though)
      Any suggestions would be greatly appreciated.

      Thanks

      Comment


      • #4
        Re: Hesitation on 99' GP1200

        dirty internal fuel filters in the carbs, sticking needle not popping off, creased chk valves not pulling fuel thru...any of the three could cause a lean hesitation, imo.

        i'm thinkin a carb rebuild at 70hrs and 5 yrs might be due..esp if you still have a choke.

        SBT has the best deal goin' with their house brand mikuni rebuild kits.
        97 venture11/1200, 01gp12r stage1, 02F12X
        dav_dman@yahoo.com

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        • #5
          Re: Hesitation on 99' GP1200

          The more I read, the more I think you are right.
          I am making adjustments to the low speed screws for a symptom that they are not designed to fix. (The Mikuni manual clearly states that).
          Does SBT sell pop-off testers. I sure need to find one.

          Thanks

          Comment


          • #6
            Re: Hesitation on 99' GP1200

            www.watercraftmagic.com
            SBT Tech Support is here to help with your problems.
            We try to answer each question quickly and accurately.
            Please do not use Private Messaging for Tech Support, use the forums.

            Comment


            • #7
              Re: Hesitation on 99' GP1200

              Take Dav_Dman's advice... rebuild the carbs as they are probably due. Don't forget to order new 1.5 needles/seats as well. I highly recommend going to the following setup:

              1.5 N/S
              115g (gold) springs
              100 pilot jets (only #1 carb uses a this size stock so need to order 2 more)
              135 main jets (same as stock so don't need to order)

              Make sure the pop-off pressure is between 50 and 55psig and all three carbs popoffs must be +/- 1psi of each other. Also, its highly recommended that you replace the carb-to-manifold gasket as well to minimize the chances of an air leak.

              Set the low/high carb needle adjusters as follows to start:

              Lows:
              all 3 carbs 1 turn out

              Highs:
              #1: 3/4 turn
              #2: 1 turn
              #3: 3/4 turn

              You can then dial them in once you are on the water (best way is using a good tachometer).

              This is also a good time to replace the main fuel filter as well as switching over to premix if you have not done already. Good luck and let us know if it works out.

              Comment


              • #8
                Re: Hesitation on 99' GP1200

                If your going to remove the carbs and check the internal fuel filters (great suggestion) and check the pop offs, then by all means order a primer kit and remove the choke plates.

                In addition to that I would go the distance and order 3 Fly/Prok style flame arrestors and do away with the stock air box entirely. This will greatly simplify carb tuning/inspection plus give you the crisp performance you need. Basicly 1.5 N&S are still used. Spring is changed for lower pop off , main jets stay the same and the pilot jets will need going higher.

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                • #9
                  Re: Hesitation on 99' GP1200

                  Thanks for all the great info. I'll get a list together and get the parts ordered and let you know how things turn out.

                  I don't know what I would do without forums like these.

                  Thanks

                  Comment


                  • #10
                    Re: Hesitation on 99' GP1200

                    DTD--- those carbs are notorious for creasing the check valves on the fuel pump side of the carbs--- check them out while you are inspecting the internal filters. Due to the age and the hours--- you may want to do a complete rebuild of the carbs
                    SBT has good prices on their rebuild kits. We have the OEM Mikuni in stock.
                    We usually keep everything for those carbs in stock from primers to f/a's, We also make t-handle adjusters for those carbs. Feel free to call if you need any help while your doing the work.
                    www.ISLANDRACINGPERFORMANCE.com

                    www.ISLANDRACING.net

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                    • #11
                      Re: Hesitation on 99' GP1200

                      Just wondering - What are the stock carbs on the 99 GP1200 - SBN44, BN44...?


                      Thanks

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                      • #12
                        Re: Hesitation on 99' GP1200

                        Sbn 44
                        SBT Tech Support is here to help with your problems.
                        We try to answer each question quickly and accurately.
                        Please do not use Private Messaging for Tech Support, use the forums.

                        Comment


                        • #13
                          Re: Hesitation on 99' GP1200

                          t-handles sure would be handy for tuning on the water... may need to order a set of those myself!! :D

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