2006 Johnson SD 3.5 HP 2 Stroke Outboard Service Manual, PN 5006562, Page 81Get 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
Idle Temperature
Install correct test propeller and place outboard in test tank&
WARNING
IMPORTANT: For the following engine operating temperatures and RPM figures to be correct, the inlet water temperature must be 70 10 (21 C)
To prevent accidental starting of engine while changing propellers, twist and remove all spark plug leadsStart outboard and run at 3000 RPM for at least five minutesReduce engine speed to 900 RPMAt 900 RPM, the digital pyrometer or Temperature Gun should indicate 140 15F (60 rC) when checking at top of the cylinder headIf engine temperature does not exceed 100 F