650sx CDK2 38 tuning
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  1. #1
    PWCToday Regular
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    650sx CDK2 38 tuning

    Hi All,

    have an 88 650sx with a 91+ CDK 2 38mm and proper sized intake manifold, smoothed out exhaust ports, stock 39mm non diverter exhaust manifold, mariner head at 170psi per cylinder, and a stock pipe that has had 4in added to the center section.

    The carb is jetted stock, 75 slow 140 main. I took her out last week after getting her back together with this newer motor / exhaust and had to turn the high speed out to ~1-1 1/8th of a turn from the sock 5/8ths. It seems to run well, but water was rough so i couldnt do much in the way of long WOT runs.

    Needless to say, my questions are. 1. how far out is too far on the high speed before i should consider going to a bigger main jet, 2. what do others think my jetting / screw settings should be for such a setup?

    Thanks!

  2. #2
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    Re: 650sx CDK2 38 tuning

    Wow... no one has ever tuned a CDK 2 38mm on any 650 motor... i find that hard to believe considering its a stock carb.

    Just looking for starting points.

  3. #3
    PWCToday.com Is My Home Away From Home Rushford_Ripper's Avatar
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    Re: 650sx CDK2 38 tuning

    Usually between a 1/2 turn and 1 and a 1/2 turns out is good, anymore you would usually go up or down on jets


  4. #4
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    Re: 650sx CDK2 38 tuning

    Awesome.

    Any tips for idle to half throttle tuning. Ski runs great but has just a smidge of a bog if you wack the throttle from a dead idle.

  5. #5
    PWCToday.com Is My Home Away From Home bandit88's Avatar
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    Re: 650sx CDK2 38 tuning

    Quote Originally Posted by nd4spdbh View Post
    Ski runs great but has just a smidge of a bog if you wack the throttle from a dead idle.
    Bog or hesitation? Bog = go leaner on the main jet, hesitation = go larger on the main jet.
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  6. #6
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    Re: 650sx CDK2 38 tuning

    Quote Originally Posted by bandit88 View Post
    Bog or hesitation? Bog = go leaner on the main jet, hesitation = go larger on the main jet.
    Ya know ill definitely have to play with it more on calm water, admittedly it was rather rough and rather hard to do tuning. It SEEMED to get worse the further out i turned the high speed screw.

  7. #7
    PWCToday Newbie Setbrew45's Avatar
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    Re: 650sx CDK2 38 tuning

    Following this post, I just got a 145 main 80 pilot ordered from sudco. I will let you know how that goes. Hope I guessed right at 10 bucks a jet!

  8. #8
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    Re: 650sx CDK2 38 tuning

    Quote Originally Posted by Setbrew45 View Post
    Following this post, I just got a 145 main 80 pilot ordered from sudco. I will let you know how that goes. Hope I guessed right at 10 bucks a jet!
    What kinda mods to your ski?

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