compression/carbon issue?

seeko

Recruit
Joined
Sep 6, 2008
Messages
1
I have a 1977 6hp johnson model #6R77M. The engine starts fine but will not go past a fast idle. linkages are fine. compression is 60 to 70 in both cylinders with some bleed down in each. spark is good in both cylinders. there is probably a fair amount of carbon deposits. any ideas?
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: compression/carbon issue?

dirty carb, clean, rebuild kit. then do a decarb.
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
 

kenmyfam

Supreme Mariner
Joined
Aug 10, 2006
Messages
14,385
Re: compression/carbon issue?

Seafoam is just great for this. Enjoy the smokescreen !!!!
 
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