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  1. #1

    Join Date
    Sep 2008
    Jervis Bay

    Polaris MSX150 idling high after rebuild?

    Hi Guys,

    Great info on this forum, has helped with issues on this MSX!
    Just had a rebuild on this MSX150 due to spark plug tip breaking off, scoring & delaminating the bores. So had new sleeves & pistons fitted.

    Prior to problems with delamination, this motor used settle down to an idle of around 1800rpm in a few minutes, running on the flushing hose. Now since rebuild idle speed will not settle down stays at just over 3000rpm (in reverse).
    Have not tested it in the water yet, could there be a leak in the intake somewhere causing it to idle higher?
    I know of another MSX150 that idles down under 3000rpm after a few minutes running on the flusher hose.
    Curious to see what other uses are experiencing in terms of revs. If other MSX150s are idling high, then I will test this in the water on the weekend. If not I may just have to check out the problem first.

  2. #2
    Join Date
    Jul 2007
    Cedar Rapids,Iowa
    I would think out of the water, with no load on the prop, 3000 may be about right,Try it in the water strapped down good on a trailer,I think you'll see it at about the right idle rpm.

  3. #3
    Jet Ski Tinker
    Join Date
    Sep 2008
    Williamsburg VA

    Air leak

    Their is a hose that comes from the intake manifold to the pop off valve for turbo boost. If you have an air leak it will run at 3000 rpm's. Should run at 1500 to 1800.fficeffice" />>>
    It sound that you have an air leak in the intake area. You my need to check all the clamps and hoseís and gaskets for tightness.>>

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