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fuel/air control/adjustment

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  • fuel/air control/adjustment

    What is the proper way to adjust the Lean/Rich adjustment on an older style 9.9 Johnson? The knob works, and you can tell a difference when you turn it, but you can pull the knob off, and reinstall at a different setting. Since this engine is new to me, I'm wondering if, after years of use, that it is way out of adjustment? Is there a way to tell? or should just adjust it until the engine runs best at idle? at high rpm?Also, if anyone knows where I can find the rubber boot that covers the stop button, I'm in the market for one.

  • #2
    Re: fuel/air control/adjustment

    try ckg out this place: http://www.maxrules.com/johnsonboatmotor.html


    • #3
      Re: fuel/air control/adjustment

      Ebbtide, its good to hear about your experiences in Valdosta. I love Rays Mill Pond too. Actually, I don't live very far away from there. The motor idles higher and runs smoother when I turn it up to rich, but it smokes a lot more of course, and I was wondering if the richness was overcompensating for a dirty carb. or other possibilities of wear/failure. Give me something to think about guys!


      • #4
        Re: fuel/air control/adjustment

        yo waco>be sure to have fresh fuel>be sure the fuel mixture ratio is correct>have engine warmed up>adjust idle mixture screw for highest smoothest idle>reinstall knob to center of its travel *If the carb has only the idle adjustment, it will have minimal affect on high speed. In other words, the high speed mixture will be determined by an internal orfice size and float level.pardon me while I cough my brains out.....got the flugood luck!
        Alias "schematic"


        • #5
          Re: fuel/air control/adjustment

          so........I should turn the adjuster in (getting richer), until I find the smoothest idle, then reinstall at mid-range? Thats easy enough. Thanks Scem.


          • #6
            Re: fuel/air control/adjustment

            Waco,You got it. The numbers or notches you see are just reference points for your future use. You can take the knob off and install it upside down if you prefer.Just adjust the idle to where it sounds good by ear. Make sure the engine is warm though.