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  1. #1
    Member
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    May 2016
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    Atlanta
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    29

    250 ox66 question

    So I have an 04 Champion 206 with a Yamaha 250 OX66. I just put a 10" Atlas Hydraulic jackplate on it and put a 25p Tempest that has been balanced and blueprinted. The boat jumps up on plane and rides really good on the primary pad. Top speed 63.4 by myself-gps on the lowrance at 51-5200 rpms,and that's all it will turn . I know the motor will turn way more-5900-6000. What gives? Do I need to go to a 24? The motor has new plugs and compression 150 each cylinder.

  2. Moderator 21XDC's Avatar
    Join Date
    Sep 2004
    Location
    Westland Michigan
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    63,351
    #2
    My friend Mike has the same rig and gets the same results... It is heavy and slow...

    Marks Props 317-398-9294, 1850 East 225 South, Shelbyville, Indiana 46176 propellerman59@gmail.com http://www.marksprops.com/index.html

  3. Member
    Join Date
    Feb 2007
    Location
    Waterloo Iowa
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    3,770
    #3
    Your right it should turn in the 5900-6000 rpm range. I would be looking at low pressure fuel pumps and the O2 sensor. When the O2 sensor is not working the RPM will be off by 500.

  4. Banned
    Join Date
    Jun 2004
    Location
    Apex, NC
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    4,828
    #4
    Quote Originally Posted by Bigstew View Post
    So I have an 04 Champion 206 with a Yamaha 250 OX66. I just put a 10" Atlas Hydraulic jackplate on it and put a 25p Tempest that has been balanced and blueprinted. The boat jumps up on plane and rides really good on the primary pad. Top speed 63.4 by myself-gps on the lowrance at 51-5200 rpms,and that's all it will turn . I know the motor will turn way more-5900-6000. What gives? Do I need to go to a 24? The motor has new plugs and compression 150 each cylinder.
    150 psi of compression is too high. On stock heads compression should be around 115psi and on modified heads 135 psi max for pump gas. Verify compression and Tac for accuracy. Raise motor on jack plate to increase rpm and watch water pressure!! No less then 12psi.