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  1. #1

    polaris won't accelerate

    I just recently purchased a1996 Polaris 780, It ran very well the first twenty to thirty minutes I had it out, then it started running very poorly, only about 10 mph. I took it to a repair shop to find the middle cylinder had 0 compression. The shop rebuilt the carbs, and replaced the piston in the middle cylinder. I now have 135 psi on all three cylinders. The ski cranks and runs good, but same problem on the water, only goes about 10 mph. Any ideas out there on what could be the problem?

  2. #2
    David Drkvampire2001's Avatar
    Join Date
    Jul 2011
    Edgerton, Wisconsin, United States
    Welcome to the Hulk!

    you will find very usefull information here, and TONS of help from members, this is the place to be.

    When the shop rebuild the carbs and the piston, did they use Genuine Mikuni parts? did they upgrade the ski to a tripe outlet fuel pump and replace all the fuel lines? this will need to be done as that piston burned up due to a lean condition, and without all of that it could very easily happen again, also replace or rebuild the fuel selector. remember these are old machines and need some love to be reliable.

    You can start here, this will help you get on your way and learn the inside and out of the ski

  3. #3
    BlueFishCrisis's Avatar
    Join Date
    Aug 2011
    Medina, Ohio, United States
    The 96 780 already has a triple outlet as a stock item. It would be a good idea to rebuild that pump as well as the rest of the fuel system. If the motor is running well, around 6500 RPM, and you are only getting 10 MPH, its time to focus on the jet pump section. Make sure the ride plate and intake grate are well sealed to the hull. Check your impeller to wear ring clearance to make sure it is within tolerance. Make sure you didn't suck anything up into the jet pump like weeds, a plastic bag, a bottle cap, etc....

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