Re: 18 HP Johnson Outboard motor compression ratio
Compression ratio? If you mean compression readings taken with a compression gauge...anything above 100 in either cylinder is excellent, 75 is about bottom line...below that and it will be a weak performer. Biggest thing is difference between cylinder compression readings...both should be within 10-15 percent of each other...otherwise you have a weak-getting-weaker cylinder/rings.
Re: 18 HP Johnson Outboard motor compression ratio
take your readings, if they seem low, borrow another guage. remove the plugs, and turn the motor over until the guage quits going up. post your number here.
