1974 Johnson 25hp

Bgabassin

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Mar 23, 2019
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3
I bought this motor and after rebuilding the carb and still getting spark plugs with fuel on them we checked compression and got 65 i don’t know what to do next
 

Bosunsmate

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Apr 7, 2012
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6,129
Is that 65 on both? Is it a good compression tester?
You may have to take off the headgasket and look inside, sometimes also the headgaskets deteriorate with age and they are quite cheap to replace
 

F_R

Supreme Mariner
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Jul 7, 2006
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28,195
65 is way, way too low. It should be nearly double that. Are you pulling it till it doesn't rise any higher?
 

F_R

Supreme Mariner
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Jul 7, 2006
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28,195
I thought so. Pull it however many times it takes till the gauge doesn't go any higher is the correct way to do it.
 

F_R

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28,195
Perhaps a short history lesson will help. Drop back about 6 or 7 years, and motors ran great. But sloppy. They dumped a lot of excess fuel overboard into the lake. By the time yours was built, public and gov't howl forced mfrs to try to clean up their motors. On yours, they rerouted the dumping into the cylinders for supposed burning. In truth, they were still sloppy, but ran poorly. And fuel still went into the lake, but at least now it was black fuel instead of raw gas. And wet plugs were a curse. Actually, the wet plugs aren't all that bad. It should run even though.

In all fairness, cars ran crappy during those years also. They called it "smog control".
 

jimmbo

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May 24, 2004
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12,944
Perhaps a short history lesson will help. Drop back about 6 or 7 years,


You mean back in to the 1960s, not 2013

I remember our 1965 90 Hp used to have raw gas floating to the surface when it ran, no leaks at the carbs(new diaphragm in the fuel pump too), I used to think the level in the fuel tank dropped as fast at idle as it did at 3/4 throttle
 
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