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  1. #1

    Can't reach Top Speed

    I have a 1996 Polaris SL780 and replaced the float in the fuel tank in 2006 because it was stuck in limp mode. I cleaned the tank and fuel seperator,also put in new plugs. The problem that I have the last several times out is everything seems to run fine until I reach about 29MPH or some where around 4000RPM, and that's all I get. I use to be able to reach 50MPH or a little better with this machine. This PWC only has 62 hours on it if that is any factor. Also, all visible Carb functions seem to be operating properly. What could be the problem and what are some suggestions on where to start?


  2. #2
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Welcome to the Hulk. The limp mode can be tripped by low oil and overheat as well. Did you go premix and eliminate the oil tank? Is the engine getting hot?

  3. #3
    ph2ocraft's Avatar
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    BIG WELCOME to the Green Hulk Forums!!

    Here's something from the tech section.

    I remember the PRO's had this quite a bit as well as the 750's with the buzzer for overheat, I have a simple testing procedure for it.
    First disconnect the tan wire to the CDI and see if this solves the limiting problem, if so, check the temp sensor but more importantly the tan wire and it's routing for crimps, pinches and shorts. If you find no problems with the overheat temp sensor or wiring be sure to check for restrictions in the cooling system. You can of course disable the wire BUT you risk missing the overheat.
    Verify the tan wires on the terminal board are NOT grounded. If they are you will need to correct the problem. There should be no ground to the tan wires unless you have an overheat condition present.
    If all checks good, replace the CDI and test it all over again.

  4. #4
    ph2ocraft's Avatar
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    Does the red lamp at the MFD flash?
    Did you verify crank index to make sure you didn't hydro-lock the engine at any time?
    Does it sound like the RPM's are limiting?

  5. #5

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    what is crank indexing and what does it do to the ski exactly?

  6. #6

  7. #7

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    Is welding the crankshafts a good idea?

  8. #8
    Did not eliminate oil tank, seems to inject oil properly. Have not noticed any overheating due to the fact that the problem exists as soon as I put it in the water. Is there something that I am overlooking?

  9. #9
    Red lamp does not flash, RPM's top out between 4000 and 4500 and it sounds like I'm running out of fuel as it did when I discovered the problem with the fuel float and limp mode. This machine ran like a top up until the end of 2002 and then it sat for almost 3 years. If that adds any speculation! Please expand on Crank Indexing?

  10. #10
    ph2ocraft's Avatar
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    Did you put fresh gas in it? That will give you HUGE running problems.
    Did you cut the wire ends yet?
    Did you check the ground for the CDI yet?
    Run those few tests and let us know what you find, it will help point us in a direction to help you out.

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