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  1. #1

    Exclamation 1200 STX-R Overheating/Acceleration problems

    Recently bought a used 2002 Kawi 1200 STX-R ski from a family friend and having issues on the water. When I first got it, I drained and replaced gas & oil. Changed fuel filter. Rebuilt carbs (not fuel pump), replaced oil lines with clear, new battery, newer used jet pump (clearance is good). Compression check on all three cylinders were 120+ psi. Ski runs perfectly on the hose and runs water through as it should. Running on the trailer, the ski pulls water and pushes out all three pissers and exhaust. I'm getting exhausted troubleshooting this thing so I am hopeful that I can find a solution here. These are the issues I'm still having:

    1) When on the water, jet ski sounds great at idle and even has a little pull when barely giving it throttle, however, when I try to take off it just bogs down and begins to nose plant into water. No acceleration. Thought it was the jet pump so I replaced it. I did not rebuild the pump though as it looked slightly used.

    2) The exhaust manifold gets warm when on the water. Unlike running on the hose where it sweats from the cold water running through it, on the water it gets very warm. I haven't run it more then a couple minutes to know just how hot it would get but I wouldn't think it should be different than when on the garden hose.

    These seem to be the only issues I'm having. Things that I'm aware could be wrong are Fuel pump, bad reeds for the acceleration issue but as for the cooling, I haven't a clue and tired of spending time and money on this thing. Can someone please help me troubleshoot this ski?!

  2. #2
    I would start with pressurizing your fuel system to make sure there aren't any leaks. It is easy to do with a bicycle tire pump. Connect the pump to the check valve hose from the tank and pump it up to ~3-5 psi. It should hold pressure. If it is not holding pressure then you have a leak and it should be fairly easy to find since fuel should be spraying out.

    If the fuel system is holding pressure I would recommend checking the throttle position sensor. You need a special wiring harness and a multimeter to set it properly. If you didn't touch it then in theory it should be set properly. If you did remove it when you worked on the carbs then that could be your issue.

    I have noticed that the exhaust pipe does stay very cool when on the hose but it gets very warm in the water. I believe that has to do with how the water flows when on the hose versus how it flows when the pump is in the water. I believe that is normal but hopefully someone else here will confirm that.

  3. #3
    steve45's Avatar
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    Welcome aboard, Waverider!

    Tell us about your carb overhaul. Did you replace any parts? Did you use genuine Keihin parts? Did you clean the internal filters? Did you replace the O-rings on the needle valve seats and fuel rails? Did you check the pop-off pressure?

    Did you check the pop-off valves for the oil lines and did you run the oil lines to the correct places?

  4. #4
    I have seen no sign of fuel lines leaking in all the time I've been working on it. I will still look into checking though. Would the throttle position sensor only cause it to bog down under a load or would it have issues at all times while running?

    That is extremely weird that the exhaust temp would change from hose to lake water like that.

  5. #5
    Quote Originally Posted by steve45 View Post
    Welcome aboard, Waverider!

    Tell us about your carb overhaul. Did you replace any parts? Did you use genuine Keihin parts? Did you clean the internal filters? Did you replace the O-rings on the needle valve seats and fuel rails? Did you check the pop-off pressure?

    Did you check the pop-off valves for the oil lines and did you run the oil lines to the correct places?
    This is what I purchased and replaced on the carbs. https://www.jetskiplus.com/kawasaki-...1100-zxi-stx-r

    I did not not do a pop off pressure test on either the carbs nor the oil lines. I did however put the oil lines back on correctly as i did one at a time.

  6. #6
    On the hose I believe the cold water from the hose enters the pipe without getting heated from the engine. In the water the pump forces the water into the cylinders then into the pipe and pissers. Therefore the water will be hot entering the pipe so it won't cool it as well as cold fresh water from a hose does.

    I think I am correct on this. At least it makes sense to me since that is how the water flows differently from on the hose and when in the water.

  7. #7
    Quote Originally Posted by beekermartin View Post
    On the hose I believe the cold water from the hose enters the pipe without getting heated from the engine. In the water the pump forces the water into the cylinders then into the pipe and pissers. Therefore the water will be hot entering the pipe so it won't cool it as well as cold fresh water from a hose does.

    I think I am correct on this. At least it makes sense to me since that is how the water flows differently from on the hose and when in the water.
    The only thing that throws me off is when I thought it was the jet pump not pulling water through the inlet, I bypassed it with a hose (the rear entry) and ran the ski to makes sure it wasn't clogged and things ran perfectly. The exhaust was also sweating then so I'm not sure why it's so hot on the water. If this is a normal thing then I won't worry about it!


  8. #8
    I have never ran it on the hose using the line from the pump area.

    I know on the hose my pipe is cold like your describing. In the water the pipe gets very warm/hot after riding. I can touch it but not hold my hand on it.

    Hopefully someone else here will respond.

  9. #9
    steve45's Avatar
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    Perfectly normal for the exhaust and heads to be cold on the hose and warm on the water.

    Non-OEM carb parts, I guess you didn't replace the fuel rail O-rings. Did you clean out the fuel rails and end fittings? You should check pop-off pressure when replacing needle & seat, especially if using aftermarket parts.

    Most of the time when there is a leak on these fuel systems, it is air leaking in, not fuel leaking out.

  10. #10
    Quote Originally Posted by steve45 View Post
    Welcome aboard, Waverider!

    Tell us about your carb overhaul. Did you replace any parts? Did you use genuine Keihin parts? Did you clean the internal filters? Did you replace the O-rings on the needle valve seats and fuel rails? Did you check the pop-off pressure?

    Did you check the pop-off valves for the oil lines and did you run the oil lines to the correct places?

    If the rear balancer oil line and #2 carb oil line were switched would this be a cause of the ski bogging down? Because they were.

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