souped up johnny 40

[jamason]

Re: souped up johnny 40

Sorry guys if I sounded condesending, I was trying for emphatic! I do thank all who gave there time and expertise in this thread. I also think this thread is probably too long and your right, a lot that was said tends to get overlooked during this busy time of year. I'll start a new thread if the used flywheel that I ordered doesn't fix the problem. Thanks again for your responses. P.S. So you see where I'm coming from, the following quote is from my official Johnson Service Manual; "Weak flywheel magnets can also cause low voltage readings on ignition test equipment". Seems strange of the Johnson folks to say something like that if magnets never go bad!

 

[Paul Moir]

Re: souped up johnny 40

I'm not saying it's impossible (sorry; my 1947 statement was hyperbole for emphasis), just very very rare. Search the J/E repair forum for "weak magnet" and you'll see what I mean.<br /><br />So what can weaken a magnet? Excessive heat (probably way more than normal overheating) was the only thing that came to mind for me. But there is a possibility I just learned about, where your rectifier fails shorted and 12v is leaked into the charging coils, but not enough to burn the coils. This sets up alternating N and S poles that the magnets are forced to pass over which can weaken them and cause a lot of excess heat.<br /><br />I'll be interested to hear what the problem turns out to be. But do try to do a plugs out test to get the Hz up closer to where the meter is designed to read them.

 

[jamason]

Re: souped up johnny 40

The used flywheel had no effect on the cranking test, same output. So there goes the weak magnet theory. The cranking test was previously performed with the plugs out and a slight increase in voltage was noticed, up from 106 to 126 vac. I give up! This thread is too long for anyone to understand and I've run out of things to check. I've read a million other threads and replaced or checked the entire electrical and fuel system, even got a new prop, sized right for the boat. But its still dies when the fhrottle is advanced from idle through mid range. However one time I was able to tease it past the point of failure and it took off like a rocket and ran great until I cut back on the throttle then it started the same sh-- all over again. Can't be the carbs as I cleaned and fished wire thru every port in them 3 times, upsized the jets and installed boyesens reeds. <br /><br />I guess I'll just go to the skyway pier and fish like a landlubber, or was that landlover? It's late and I'm ramblin so thanks to all who participated and goodby.

 

[Chinewalker]

Re: souped up johnny 40

HighNDry,<br /> Don't give up the ship just yet! Next time you're attempting to plane off and it's bogging, try bumping the choke. If it picks up then you're running lean. Could be a vacuum leak, could be wrong jets, could be a mis-adjusted float. If it bogs even more you could be running too rich, which may be a factor of the bigger carbs and wrong jets.<br /> Also, if you can get it through the flat spot again, run it hard then shut if off immediately. Tilt up the motor and grab your plug wrench. Pull the plugs and take a look at what color they're burning. Real dark could mean too rich, real light would mean too lean. <br /> Finding a set of 40hp carbs to fall back on probably wouldn't be a bad idea. Having a "souped up" motor isn't worth a darn if it won't run at all.<br />- Scott

 

[jamason]

Re: souped up johnny 40

JETS, JETS, JETS; it's all in the jetting! Runs fine with the right mix of jets. Took 6 trips to the water and 12 different sets of jets but it goes like a bat out of hell now.
Thought y'all might like to know how this problem finally got worked out.

 

[Paul Moir]

Re: souped up johnny 40

Thanks for the comeback!
With all the performance goodies available for outboards, I'm surprised no-one sells carbs with adjustable mixture controls like the old style ones.