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idles on bypass, won't idle to engage prop

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  • idles on bypass, won't idle to engage prop

    Working on a 1995 Johnson 50 hp. VRO working - New carb kits in both carbs. I have the linkage adjustment instructions and have followed them. here's my problem: To start and idle the engine I have to use the bypass lever. But it will idle and idle and idle . To engage the prop it has to be a quick motion of drop the bypass level and engage the prop and then she goes. IF it will idle with the bypass I should be able to find an idle without the bypass in my opinion. What am I doing wrong? I see the bypass advance the linkages, but the engine starts and idles before the throttle plates open- as long as I use the bypass' advance. I'm at 5300 ft elevation is that it? At a loss otherwise.

  • #2
    What is the idle rpm when you use the cold start lever? Have you tried adjusting the idle screw itself? What is compression? Do you have spark to both cylinders? The carbs have nothing to do with idling that is set with timing only> Your idle speed needs to be set in gear on a warm motor.

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    • #3
      edited

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      • #4
        Blocked idle circuit in the carb top will give you issues, as well as a blocked jet at the bottom of the bowl (behind the screw plug). How did you clean the carb? In addition to the engine throttle idle screw, your carbs have a mixture needle (probably needs a richer setting for high altitude). Should idle before the throttle plates open if the engine is warmed up and properly adjusted without the warm up lever engaged. Measure spark with an adjustable open air tester.

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        • #5
          Also verify that the two rollers, one on timing cam and other on throttle cam pickup, are complete. They have two layers, the outer layer commonly falls off making idle adjustments nearly impossible.
          '47 18' CC Utility "Knock On Wood"
          Various Evinrude powered Pontoons all named "Floosy" I've realized that 1/2 the population is above average intelligence, wish I was in it.

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          • #6
            If I could just work on this forever and never try to make a living - sorry to not follow this quickly. Carb bath for carb cleaning, disassembled and only metal parts in bath. New cam rollers, too. I'll have to get the rpms. Idles down to nothing before it stalls.As long as it's the bypass lever. Compression cold: -throttles closed 75#'s and 76#s. I've ensured the idle circuit is not blocked, unless I missed something.

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            • #7
              Oh and idle screw adjustment has some effect, but not a lot.

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              • #8
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                Compression should be 120 PSI.

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