1st make sure measure correct.
2005 manual
" 1/ run out board till full operating temp reached, shut down
2/disconnect crank shaft position sensor
3/move throttle linkage to WoT
4/ turn over on starter measure max pressure on each cylinder

Sry cant find pressure specs.. I would think around the 115lbs ???.. Thu what looking for is difference between cylinders. Anything over 10/12% indicates something wrong.

Also a engine that has a build up of carbon in the chamber has a higher compression, assuming that the rings etc in good condition .. hence why looking at the variation.

Thanks for the reply Steps and Smudge

I had my outboard serviced and on the report it says
1) 125
2) 120
3) 125
4) 120

Cheers :)

Excellent news , thanks Steps