Fouling plugs

[glenngamblin1]

I have a 1979 140 hp evinrude that runs great from 1/4 throttle up to full throttle. Below 1/4 throttle it misses and hesistates pretty bad. When i checked my plugs, the right side 2 cylinders have wet plugs and the left side looks dry. It's had a carburetor job and I'm a bit puzzled by it. This motor started out as a 115 hp evinrude, but the case was replaced with a 140 and is supposed to have everything new in it. I'm fixing to do a compression check on it, but I would appreciate a little guidance on what this problem could be.

 

[Dhadley]

Re: Fouling plugs

Welcome!<br /><br />What plugs and fuel are you using?

 

[glenngamblin1]

Re: Fouling plugs

Thank you,<br /><br />Champion L77JC4 plugs and 92 octane fuel with quicksilver oil at 50:1

 

[Dhadley]

Re: Fouling plugs

Good choice on plugs and oil but I would strongly recommend the fuel (87) that the motor was intended for.<br /><br />Each carbs will affect the cylinders across from each other (given they are built and operating correctly). Ignition will affect the cylinders from side to side. I would be concerned about why the port plugs are dry. <br /><br />Are they dry and "sooty"? Are they dry and clean?

 

[glenngamblin1]

Re: Fouling plugs

Does anyone know the proper jets to use on this engine. I have a manual that I ordered but I am a little impatient. The plugs are dry and sooty. I did a compression test and all cylinders were 120 psi. When you said that the carburetors affect the cylinders across from each other, do you mean on the other side of the block from the carb. Please forgive me, I'm a veteran motorcycle mechanic but I don't know jack about boat engines.