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  1. #1

    Join Date
    Jun 2011
    Location
    Colorado
    Posts
    2

    99 XPL help at high altitude

    Just wanted to introduce myself and ask a couple of questions for the high altitude guys. Currently running a 99 XPL at 5250 feet and the boat has a concord 15/20 prop, Stock everything else. I am currently turning this prop at 6100 RPM'S and thought that sounded a little low. Should I get the SeaDoo High Altitude prop (271000931) to try to get some more RPM's? What is the optimum RPM's to run? The boat has been jetted and runs great. Compression is also low at 107 each cylinder at this elevation. What head mod should I try to get this compression up to factory sea level specs? No race fuel for me. Thanks for the help.


  2. #2
    I ran a GTX Limited 951 at that altitude. It had about that compression. I also had a 787 GSX that had a cut head, rejet, pitched impeller, etc. The GTXL turned about 6200 rpms, low 50 mph. The 787 was similar before the mods. After the mods, the rpms went up to 6600, but I lost 2 mph on the top end. The biggest thing is the repitch. You can have the head milled, or buy an aftermarket head.

  3. #3

    Join Date
    Jun 2011
    Location
    Colorado
    Posts
    2
    Tried advancing my timing 2 degrees this weekend and the boat ran worse. Have a high altitude prop on the way. I will try this first before messing with the timing again.

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