1991 Johnson/Evinrude Models "EI" 40 thru 55 Service Manual, Page 51Get this manual
Engine Idle Speed Adjustment 1The boat and engine must be in the water under normal operating conditions with the correct propeller installedThe boat's movement must be unrestrained The boat must not be tied to dock or trailer2 Start the engine and allow it to reach normal operating temperature 3Check idle RPM in FORWARD gear with an accurate tachometer 17 ill "'"