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Hello my name is ***** ***** am I speaking with? I read what you wrote. The one with 122 PSI probably has a bit of carbon build up on that cylinder, causing a bump in compression. I would go to an Evinrude dealer and get a can of what is called "Engine Tuner". Engine Tuner is a decarbonizer. Just follow the directions on the can, run the product through the engine as directed. Then retest your compression and see what happens. If for some reason the compression does not come back down, then you have 2 choices from here. Either run it. Or, take the heads off and see if the engine has the right piston in it or not. On this specific engine compression numbers in the 90's would be typical and expected, its' the one at 122 that is a surprise. There is really only 2 things that can cause that, either lots of carbon buildup, or somebody has been inside of that engine at some point and installed the wrong piston in it. Does that all make sense. I do want to make sure you are happy with my service before you go. If you had a further or more specific question on the issue by all means feel free to ask. If not, Just in case you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. The ratings box is located at the top of the screen. To rate, you must select the star you wish and also confirm it. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, or if you can not see the ratings box which is at the top of the screen. Please reply back "I rate Jason's service _______" and fill in the blank.
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Well, that depends on what the problem actually is. If it's carbon buildup, that is correctable with the Engine Tuner. But if it's not carbon buildup, the only other explaination is that somebody tried to rebuild that engine at some point, and installed the wrong piston in it. If it's the latter that is the case, then yes, it's not good for the engine to run that way, and the engine will likely fail prematurely unless the problem is corrected.
The problem with sea foam is it's weak. It is just not that strong. Evinrude makes the one called Engine Tuner. If you have a Mercury dealer near by they make one called Power Tune. If you have a Yamaha dealer close they make one called Ring Free. All of these products, the Ring Fee, The Engine Tuner, the Power Tune, they are all much stronger than sea foam. Personally I wouldn't waste the time or money on sea foam, I would just get a can of the strong stuff.
You are very welcome. Please do not forget to select a 5 star rating for my service. Thanks again and good luck! -Jason