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  1. #1

    99 slth fuel problems

    Yes me again, I put the ski in the water today after so tuning that I did and have a few questions. I rebuilt the carbs and replaced the old grey fuel lines with the normal black ones and was hoping that would fix the bogging problem that I was having. It did in a way but still have a little miss WOT. Came back in and put new plugs in and ran it agian, ran great. Rode for about and hour about 15 mins at a time and it just got worse. At about 3/4 throttle it was sounding great i was getting around 6000 rpms out of it but as soon as I would open it up it would cut back to about 5100 rpms, back down to 3/4 and right back to around 6000 +/- a couple. Was done riding so came home to make some adjustments but couldnt find any thing to adjust but the cap limiter and the idle mixture screw and that only turned 1/4 of a turn if that so I left it alone. pulled the plugs and they looked great as for as the color, the only thing was, was that they were soken wet with fuel. Can someone please help


  2. #2
    ok so after I wrote the last post I did some research and found what I was looking for as for as the high and low screws. the low screw is the screw that only turns about a 1/4 of a turn the high one is just above it. So I went to the ski to take a look and I dont have a hole for the high screw and you guessed it right I dont have the screw. I doesnt even look like the hole is even treaded for the screw. It has the CDK II carbs. Again can someone please shead some light on this for me.

  3. #3
    casey67's Avatar
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    Sometimes the service manaul is confused and confusing.

    The 38mm(also the red or blue 42mm) keihin carbs use a high and low speed adjusting screw.

    The 40mm carbs only have a low speed adjusting screw. The adjusting screw( gold or silver color) has a black plastic cap over it.The cap will limit/hold the screw from turning more than an 1/8 turn. This cap simply slides on and off the screw.

    Checking the plugs needs to bo done under the conditions you are trying to diagnose. When you are having the problem,such as WOT(wide open throttle) hit the stop button when you are WOT and check the plugs then.Make sure you run atleast 100 feet.Black center porcelane=rich(too much fuel) Tan/light brown=good, White=lean (not enough fuel/too much air)
    To adjust the high speed mixture(WOT) on a 40mm carb you need to change the jets.In your case,the jets or carbs are probably restricted/dirty or not getting enough gas.

    When you run it on the trailer,the plugs will be wet.

  4. #4
    thanks for the info the carbs are freshly rebuilt, took them completly apart and cleaned them and replaced everything. I didnt replace the jets because the guy that I got the ski from said that nothing was done to the carbs so I could only assume the the jets are stock. They have a 2.0 stamped on them, dont know it thats stock or different ones. If I dont have a HS screw to adjust and its bogs on WOT are you saying that I need to find a smaller main jet.

  5. #5
    casey67's Avatar
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    The stock jets should 142 stamped into the side, top ridge.

    You need to check the plugs to determine what it needs.The answer depends on what it is actually doing.

    I agree,the stock jets should work properly,you need to find the actual problem.

  6. #6
    la90043's Avatar
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    seems to me you're not pumping enough fuel...............................

    fuel pump.............................................. ................................

  7. #7
    so what everyone is saying is that its not getting enough fuel. Even though its bogging and smokes like crazy WOT it still isnt getting enough fuel. Im just trying to understand before i go and start replacing other things

  8. #8
    la90043's Avatar
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    your ski is very tempermental regarding fuel. if you dont have a fuel history of service/rebuilt/replace of the fuel system you'll run into problems and frustration. rebuild the fuel pump and check the the petcock is opening fully internally when you have it in the on position. also check your "air" check valve leading out of the fuel tank for proper operation. that $2.00 piece can destroy apiston or a whole motor.................

  9. #9
    la90043's Avatar
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    Quote Originally Posted by la90043 View Post
    your ski is very tempermental regarding fuel. if you dont have a fuel history of service/rebuilt/replace of the fuel system you'll run into problems and frustration. rebuild the fuel pump and check the the petcock is opening fully internally when you have it in the on position. also check your "air" check valve leading out of the fuel tank for proper operation. that $2.00 piece can destroy apiston or a whole motor.................
    also grab the fuel out line coming out of the fuel tank and blow into it so that to blow air back into the tank. that can clear or let you know you have an obstruction at the pick up line insude the fuel tank..............

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