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  1. #1

    97 kawasaki stx 1100 carb help

    i have a 97 stx 1100 it boggs down when full throttle if you let off the throttle for a split second and gun it again it takes right off.. the carbs were rebuilt because the last owner let gas sit in the tank and carbs for a few years.. so i sucked the old fuel out of the tank and checked compresion it 110 in each cyl and put new plugs, fuel lines, and new filter.. what can i try next please help????

  2. #2
    btldigger's Avatar
    Join Date
    Feb 2007
    lebanon tn.
    /hmm fuel pump mabe pulse line.

  3. #3
    if it was a pulse line would it do it everytime?? because it does it 7 out of 10 times and its only from idle it you keep the rpms up it runs perfect

  4. #4

    Carb Problem

    PM Sent... From the description I had the exact same problem on my 1100 ZXI and they both have the Keihin Triple Carbs... Very easy fix...

  5. #5
    Problem is more than likely the Accelerator Pump.. Had the same problem with my 1996 ZXI 1100... I had two problems.... 2 of the 3 nipples in the carbs clogged up from the accelerator pump and had a missing "o" ring in the Accelerator Pump housing that created a leak in the system... Bogged bad on take off at WOT, but if I went slow it was fine and same problem in mid range.

    Cleaning out the crud in the nipples helped and gave it a decent spray, but not enough... Inside the accelerator pump housing belongs a little "o" ring to seal the cover to the pump. No "o" ring you have a leak because it is metal on metal.

    Here is the weird part...

    If you look at the Keihin parts manual for these carbs their is no part number or picture of this "o" ring in their diagram that goes into the pump housing, but they do show a "U" ring on the diapragm shaft....

    If you look at the Kawasaki diagram on these carbs they do show this "o" ring that goes inside the housing to seal the cover to the housing, but they do not show a "u" ring on the diapragm shaft...

    I am no expert on fixing these, but have been working on them for a lot of years and see tons of posts on bogging problems with carbs that have accelerator pumps. My best guess would be it depends on if you are looking at the Kawi diagram or the Keihin diagram when trying to figure this out... Gotta have both parts and why both parts diagrams are not exact I dont have a clue...

    Long story short on what the accelerator pump does is this.. Air is lighter than fuel and rushes in on WOT and the fuel lags behind. The accelerator pump was added to give a blast of fuel down the throat of the carbs to compensate for this sudden rush of air to create the right mixture. If you have to double pump the throttle to take off you either have clogged nipples from the accelerator pump or a leak in the system not delivering enough fuel to these nipples...

  6. #6
    Texan78's Avatar
    Join Date
    Feb 2010
    N. Texas
    I am not going to disagree with Marty because he knows his 1100's. We have talked about mine through email before for my 1100 ZXi. It is possible though since you said it was all gummed up. What catches my attention is you said you rebuilt the carbs and once it does takes off it is fine. So before you go tearing down the carbs looking for a problem that may or may not be there do this first to make sure it is the accelerator nozzles.

    With your flame arrestors off and the fuel selector on start the ski and pull the throttle. You could possibly try this without starting it as long as the system has pressure. When you pull the throttle whether running or not you can see if the nozzles are shooting fuel down the carb throats. It may be possible that you just need to blow the nozzles out because they may be clogged if you don't see fuel shooting.

    If you see fuel coming out of the nozzle then it is not your accelerator pump or nozzles. This is what I really think is wrong since you rebuilt the carbs. These carb kits come with three springs. May not be noticeable by eying it but they are different grams and lengths. If you replaced those springs with ones in the kit then your pop-off is now off and you will need to set it again by cutting the coils down till the pop-off is right or put the ones that came out back in if you still have them since they are probably already set. I had this exact problem you talked about and was taught a easy way to set these without a pop-off tester in case you don't have one.

    Now this won't work on all skis, just for the 1100 with the Kehin Triple. What you want to do is use 11 gram 8.3 mm spring. Cut the coils on the springs down until the arm sits perfectly horizontal just sitting on top of the spring without tighten it down. Do this on all 3 and tighten the arms down once they are sitting perfectly even eying it at eye level. Until you get close you can cut a coil off at a time. If you use the springs I noted above it is about 4 1/2 coils give or take. Once you get close just cut about a 1/4 to 1/2 a coil at a time. Then set your mixture screws to the stock setting maybe out a little richer about 1/4 out until you know the pop-off is set then you can start to tune by starting with your idle, then low, then high, and start to lean those back until the plugs look right. Highs are a little tricker because you have to just up to speed and pull the lanyard and let it coast into the shore or bank and tune it or you won't get a accurate reading for the high. The lows you can do on the trailer as well as the idle. That should take care of the rich bog you are experiencing. If all goes well you should get the crisp throttle response you are looking for from idle to WOT. If you would rather use a pop-off testing you should be looking at a range of 12-15 psi. Like I said, I can't speak for other skis but this method works for this motor and carbs as taught to me by someone who use to race a 1100 ZXi. Now you can run it with the screws turned out past the stock setting to see if the pop-off is set. Once you know then that is when you can start tuning the screws. I always says it is better to be slightly richer then lean. But the close you can get to lean without being to lean is what you are looking for.

  7. #7
    i worked in the ski today the acceletor pump looks like it shooting gas into the carbs but i took it apart the diaphragm looks ok but i noticed that i have the little oring on the cover plate but it dont have any u ring on the shaft
    the ski runs great if i dont let it idle all the way down it pulls real hard if i let it idle down i have to either double pump the throttle or wait a couple of seconds for it to take off please help im at a loss please help
    and im not sure about the popoff pressure i used the srings that were in the carb before i rebuilt them but i just bought it used and the high and low idle screws were out 2 and a half turns so it think the popoff is way off please help

  8. #8
    Texan78's Avatar
    Join Date
    Feb 2010
    N. Texas
    If you have to turn your mixture screws out past 2 turns you are way to rich and the pop-off is off. Cut the springs down until the needle arm sits perfectly horizontal. You are going to need to eye it once you get close to getting it that way though.

  9. #9

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