Ok, went and got a higher end compression tester to see if my obviously cheep one was junk. The original readings were all 3 between 70-80. The better guage shows top-115, mid-110, and bottom 120. I assume these numbers are acceptable for a 1977 year motor ?
Motors that have sat unused for long periods of time sometimes has the rings stick and causes low compression readings. Thus the reason for using the power tune and other additives. Once the motor is running, try another comp test....results could be different !
Kinda what I am thinkin too. Once I get er runnin I will do the decarb process then dump a can of sea foam in the tank . Mite just bring the Ole motor back to it's youthful days.
You could get some Power Tune/Engine Cleaner/ CRC's GDI Intake Valve & Turbo Cleaner, remove the Spark Plugs. With the engine tilted up, spray some into each cylinder, let it sit a while, rotate the engine a 1/2 rev and repeat.
seafoam sure cleared up my honda snowblower hick-ups (surging) !
I was going to swap in a new carb ( from amazon) but never had to after I ran seafoam . Been good now 2-3 years
Running it more and testing it warm will help bring the numbers up but your numbers are acceptable to me.
Learn how to resurface the head if you haven't already and send pics of this motor (whole and under the cowling) to see if you need other info to keep this wonderful outboard going.
