2004 SR Johnson 2 Stroke 9.9, 15, 25, 30 HP Outboards Service Manual, Page 174Get this manual
POWERHEAD ENGINE TEMPERATURE CHECK
ENGINE TEMPERATURE CHECK
Temperature Gun, PIN 772018, or digital pyrometer should be used to accurately determine the engine's operating temperatures
Reduce engine speed to 900 RPMAt 900 RPMthe digital pyrometer or Temperature Gun should indicate 140 15F (60 rG) when checking at top of the cylinder headModel IDLE Temperature
If engine temperature is not within this rangetroubleshoot cooling system to determine problemSTEP Increase engine speed to 5000 RPM At 5000 RPM, the digital pyrometer must not indicate more than 160F (71 0G) Model
Temperature Gun