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  1. #1
    Pain is fear leaving your body.... rlovebk's Avatar
    Join Date
    Aug 2008
    So. Cal.

    Gas and Piston wash?

    Hi. Was wondering if it is better to use 91 in these skis. Also, I see alot of talk about "piston wash". What is it and what does it look like. Some day, I will be a mechanical genius, but until then, I will continually reveal my true self, dum dum. Doo!!

  2. #2
    You should be running premium 91 octane or better, preferably from sunoco or some place that has little or no ethanol.

    And I believe you can find good info about piston wash in the tech section.

  3. #3
    Moderator beerdart's Avatar
    Join Date
    Aug 2006
    Never run higher octane than is required for your compression. Higher octane burns slower and you will lose HP if its not needed. Piston wash refers to the fuel washing the carbon off the piston top. You want to see some clean(washed) spots near the intake and exhaust ports. A solid black (Flat black) piston is running lean..

  4. #4
    Race, wreck, repeat delagem's Avatar
    Join Date
    Aug 2006
    Homer, NY
    I'm running premium in my skis because I never figured out why my last piston burned down, and suspect detonation. A higher grade of gas gives me a little more cushion. But Beer is right, higher octane is created by the addition of N-Heptane, an anti-knock additive, which will reduce horsepower by a very little bit.

    Here's a pic of good piston wash on a very ugly Kawi motor! The shiny spots should look be about the size of your little fingernail, or a little larger.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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