compression

virgil47

Cadet
Joined
May 25, 2009
Messages
23
I checked the compression on my 1974 25 hp Evinrude today. Top cylinder was 118lbs and the bottom was 122lbs. I think that is pretty good for an engine that is 35 years old. Does that seem about right to you?
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: compression

do a decarb periodically. and maintain. it will be running with grand kids.

Decarb, take a can of seafoam put 3/4 of it in the gas tank, with only 1 gallon of premixed gas. put the rest in a spray bottle. start the engine, and let it come up to temperature. then remove plugs, and them some real good shot of seafoam into the cylinders, replace plugs, let sit 15 minutes. restart, and spray the rest of the seafoam into the carbs, so the the motor almost stalls, wait and repeat until the seafoam is gone.then take for a wide open spin. then put in new plugs, ad premixed gas to the tank, and take it for a wide open throttle spin. it is going to smoke like a house on fire, during this process.

afterwards compression.recheck
 
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