compression

SEAN ALLISON

Cadet
Joined
Jul 18, 2008
Messages
9
can not find what the compression should be on a 77 115 hp i have a selco manule but can not find it in book what i have is 100 psi/100psi/100psi/98 psi is this ok
 

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Re: compression

Those numbers are great. You want the difference between cylinders to be within 10%. You are well within that variable. No problems.
 

tashasdaddy

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

no problems. i would do a decarb on it, probably has never been done. it's like an enema for the motor, gets all the built up crud out.

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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