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  1. #1

    Hole in #3 piston

    I have a 94 750stl. I need some help. I just had the eng rebuilt i took it out on the lake i was out like 15 to 20 mins and it burned a hole in the #3 piston. I took it bad the the guy that did the work and he put another piston in and said try that. Will i did and it did the same thing. Here are some of the things that has been done like I said before the eng has been rebuilt the carbs have been rebuilt new fuel pump up graded to the 3 out put pump all new line from in side the tank to the carbs. The last time i did notice that the #3 piston was a lot hotter then the rest of them. Any help out there please.

  2. #2
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
    Join Date
    Oct 2006
    Cleveland OH
    Fuel selector valve?

    Carbs not adjusted properly?

    Fuel pressure/missing fuel restictor?

    Air leak?

    Improper timing?

    Out of phase crank?

    etc.... etc..... etc.....

    1. Did the guy do a leak down test after the rebuild?

    2. What's the fuel pressure at idle? And at WOT?

    3. what are the carbs set at?

  3. #3
    I'm addicted to Polaris PWC ghostinstallations's Avatar
    Join Date
    Aug 2011
    Rochester, New York
    I would check all the stuff that xlint said. But after it is repaired, dont just go rail on it. Take it for a spin, and open up the throttle for no more than 3-4 sec each time, then let off some. The idea is to vary the throttle. This way you can develop piston wash and see how its running and make adjustments accordingly.

    Best of luck!

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