Results 1 to 3 of 3
  1. #1

    Join Date
    Jun 2011

    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
    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.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Watch "Xpl 4tec at High elevation oregon lake" on YouTube
    By Seadoodoc in forum 4-Tec Performance
    Replies: 2
    Last Post: 08-22-2016, 01:25 PM
  2. anyone else ride at "high altitude" ??
    By mongorunner in forum 4-Tec Performance
    Replies: 23
    Last Post: 07-19-2012, 05:55 PM
  3. 99 XPL lost of high rpms??
    By wickedpony2007 in forum 2-Stroke Performance
    Replies: 22
    Last Post: 06-07-2009, 07:49 PM
  4. Stage II Reliability and Positive Effects at High Altitude
    By vidbuster in forum 4-Tec Performance
    Replies: 2
    Last Post: 01-08-2008, 10:51 PM
  5. need 99 Genesis help! I'm at my wits end.
    By scottyboat in forum Polaris Open Discussion
    Replies: 0
    Last Post: 06-17-2007, 09:43 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts