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  1. #1

    Kawasaki stx 15F wont go over 6000 RPM

    Just bought this 2008 Kawasaki stx 15F ski with 14hrs on it. Put it the water has strong smooth accelation but stops at 6000RPM. Owner could not find owners book so I did not know about programming the SLOW mode and FUll out mode until after we pulled ski out of water. But checked after I came home and it appeard to be in Full Out Mode. I was able to toggle between the two modes so I am sure (at least on display that it is switching. The ski is very clean and with the low hrs I cannont imagine a lot could be wrong with it. The jet pump impellar looks good and the motoer seems to run good up to the 6K. Any ideas? i really do not think I was in the slow mode because i did not hold the Mode button down for the 7 seconds requird to change at the lake.


  2. #2
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Check the thread in my signature, then post back.

    Sean

  3. #3
    Quote Originally Posted by smokeysevin View Post
    Check the thread in my signature, then post back.

    Sean
    I read your post which is all typical mechanical checks. I have been an Master Certified mechanic for several years, having built and repaired many engines. I know anyone of these things can cause the problem, what i was looking for was a common problem (if it is out there) for this particular symptom. It just seems to run to good to 6000RPM to be a misfiring plug or injector and if it was fuel starvation it would not maintain the steady 6k we are getting out of the engine. When the engine reaches max rpm on the SLO mode what is the typical response? Does it hit like a rev limiter? or does it just stop and maintain the 6K?

  4. #4
    My ski had the same issue when I picked it up, low end was pretty good but pegged at 6, I thought it was just a turd.... Put new plugs in and BOOM 7600rpms

  5. #5
    TexasZ's Avatar
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    Change the spark plugs out for new ones, even if the old plugs look perfect.

  6. #6
    Quote Originally Posted by TexasZ View Post
    Change the spark plugs out for new ones, even if the old plugs look perfect.
    Just found small crack in exhaust Pipe where the support bracket attaches. Can these be welded? I don't see how this could cause the 6K problem but needs fixed regardless

  7. #7
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Yes they can be.

    Sean

  8. #8
    TexasZ's Avatar
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    Quote Originally Posted by Rick*j View Post
    Quote Originally Posted by TexasZ View Post
    Change the spark plugs out for new ones, even if the old plugs look perfect.
    Just found small crack in exhaust Pipe where the support bracket attaches. Can these be welded? I don't see how this could cause the 6K problem but needs fixed regardless
    I'm surprised to hear about a cracked exhaust on a ski with only 14 hours on it.
    Is the crack all the way through to where it leaks exhaust? If it does leak exhaust fumes out that will definitely cause a problem.
    It can be welded if needed...a picture might help to get a more accurate answer.

    Change the spark plugs out, that should get your rpm's back up. If that doesn't do it, take the back section of seat off along with the storage container underneath it to let lots of fresh air in. If that makes it run better, the exhaust is leaking. See Sean's post for additional info for re-doing the exhaust cuz' the connector hose between the exhaust and muffler has a couple of ring gaskets that must be aligned right when assembling the exhaust back together.

  9. #9
    slothman's Avatar
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    Quote Originally Posted by Rick*j View Post
    Quote Originally Posted by TexasZ View Post
    Change the spark plugs out for new ones, even if the old plugs look perfect.
    Just found small crack in exhaust Pipe where the support bracket attaches. Can these be welded? I don't see how this could cause the 6K problem but needs fixed regardless
    don't jerry rig it. buy a new part and do it right the first time. A new part is cheaper than a sunken ski . Also change your plugs

  10. #10
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Quote Originally Posted by slothman View Post
    Quote Originally Posted by Rick*j View Post
    Quote Originally Posted by TexasZ View Post
    Change the spark plugs out for new ones, even if the old plugs look perfect.
    Just found small crack in exhaust Pipe where the support bracket attaches. Can these be welded? I don't see how this could cause the 6K problem but needs fixed regardless
    don't jerry rig it. buy a new part and do it right the first time. A new part is cheaper than a sunken ski . Also change your plugs
    All 3 of my manifolds have been welded and as long as the welder is decent its as good as new.

    Sean

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