What should the compression be on a 90hp mercurymotor?

Answer 1

The compression ratio for a 90 HP Mercury outboard motor typically ranges from about 120 to 150 psi per cylinder, depending on the specific model and year. It's important to ensure that all cylinders have similar compression readings, as significant differences may indicate engine wear or mechanical issues. Always refer to the owner's manual or service guide for the specific model for the most accurate information. Regular maintenance and checks can help maintain optimal engine performance.