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  1. #1

    Reduces to 6,750 RPM when reaching top speed

    I have a 2005 GTX SC (185 hp). Plugs were fairly fouled after only 7 hours of use (was only getting 5,000 RPM). Now, when I give it WOT I get 7,800 RPMs. However, as the ski planes out and reaches its top speed its RPMs drop to 6,750 and hold there. Any ideas? Someone told me that the throttle cable may not be set right or loosened?

    118 hours and no error codes.


  2. #2
    Swedish Viking Craigo's Avatar
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    Quote Originally Posted by OneJESUSGod View Post
    I have a 2005 GTX SC (185 hp). Plugs were fairly fouled after only 7 hours of use (was only getting 5,000 RPM). Now, when I give it WOT I get 7,800 RPMs. However, as the ski planes out and reaches its top speed its RPMs drop to 6,750 and hold there. Any ideas? Someone told me that the throttle cable may not be set right or loosened?

    118 hours and no error codes.
    Sounds to me like slipping SC clutch washers. If you have not rebuilt your SC in the past 118 hours - rebuild it before your ski sees another drop of water!!! You might still have the ceramic washers in there! If it has been rebuilt - you are definitely going to want to check the slipping moment.

  3. #3
    JT jpt7779's Avatar
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    How many threads are you going to start? It only confuses the issue and people don't see all the history!

    Since Jerry rebuilt the SC that is most likely NOT your issue.

    Boost leaks need to be checked. Have you run the engine on the hose, revved it up and moved your hand around the IC and hoses, looking for leaks? Clamps? Sc to TB hose and clamps?

    Are you 100% sure the previous SC with ceramics didn't let go?

  4. #4
    Yes, the supercharger was fully intact when I sent it off.

    I checked all of the hoses going to and from the SC and did not see anything. All the clamps were tights. I didn't try it with the engine running (yet) but I felt around and looked and all seemed OK.

  5. #5
    JT jpt7779's Avatar
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    The reason is the intake manifold may have a split in the seam or leaking elsewhere!
    Last edited by jpt7779; 09-15-2013 at 03:26 PM.

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    Quote Originally Posted by jpt7779 View Post
    The reason is the IC may have a split in the seam or leaking elsewhere!
    Its a 185 motor, it does not have an IC...

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    JT jpt7779's Avatar
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    Reduces to 6,750 RPM when reaching top speed

    Doh!,

    I meant intake manifold can have a seam split or leak elsewhere!

    And BTW, my 185 does have an external IC.......

  8. #8
    Quote Originally Posted by jpt7779 View Post
    Doh!,

    I meant intake manifold can have a seam split or leak elsewhere!

    And BTW, my 185 does have an external IC.......

    What does IC stand for?

  9. #9
    Boost addict hotbird's Avatar
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    Ic = Intercooler

  10. #10

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    7800 rpm is over the rev limiter. Maybe you damaged the ecu? How long was the ski ran on the limiter and at what throttle position? On the 2 stroke 951s, riding the rev limiter will kill the mpem in just a few hours.

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