1988 Johnson Evinrude CC 60 thru 75 outboards Service Manual, Page 158Get this manual
Pyrometer Procedure 1Install correct test propeller and place engine in test tank ill lers to avoid accidental starting of engine
Twist and remove spark plug leads before changing propel-
2Start engine and run at 3000 RPM for at least five minutes
r:;J 3Reduce engine speed to 900 RPMAt 900 RPM, digital pyrometer should indicate 140 15 (60 rC) when held on the cylinder head If engine temperature is not within this range, troubleshoot cooling system to determine problem