1963 Johnson 75HP - Idle stop or SS adj or both?

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chops

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Oct 1, 2008
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Same info from older post...started a new thread.

Took her out for the first time on a local lake. Fired it up and it ran really well. It idled rough though. Ran it for a couple times at 4K-5K RPM and it did great. Once I got to the dock to trailer it, it stalled and wouldn't refire. I got out, backed the trailer in. Tried to start it again and it fired up but stalled. Wouldn't fire after that. I have new plugs I'm going to put in to see if that helps. I'll also check the fuel filter to see if gunk got in fuel line (new gas, old can). I think I need to make an adjustment to increase the idling speed. It looks like I have two options for doing this...Idle Stop Adjustment, or Slow Speed Adjustment on the carb. Which one? Should I do one b4 the other?
 
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Chris1956

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Mar 25, 2004
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28,547
Re: 1963 Johnson 75HP - Idle stop or SS adj or both?

Those old motors usually had the two lever controls. If so, push the throttle (in neutral) to about 1/2 and then start it.

If you have a one lever control, I would need to look at the motor to see what to adjust. The idle stop would seem to be the first thing to adjust.
 
a70eliminator

a70eliminator

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Sep 9, 2007
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3,762
Re: 1963 Johnson 75HP - Idle stop or SS adj or both?

I'm pretty sure you adjust them simutaniusly, the low speed mixture for highest RPM then back off the idle stop then again verify the low speed mixture is at it's peak RPM without sneezing and again back off idle stop, the idle stop retards the timing, eventually you should end up with the throttle plates completely closed and the idle speed is raised or lowered through timing.
 
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F_R

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Jul 7, 2006
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28,226
Re: 1963 Johnson 75HP - Idle stop or SS adj or both?

a70eliminator said:
I'm pretty sure you adjust them simutaniusly, the low speed mixture for highest RPM then back off the idle stop then again verify the low speed mixture is at it's peak RPM without sneezing and again back off idle stop, the idle stop retards the timing, eventually you should end up with the throttle plates completely closed and the idle speed is raised or lowered through timing.
Click to expand...

First thing first. Electramatic or manual shift? Different controls, y'know.
 
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