1987 Johnson/Evinrude CU Outboards 35A thru 55 Service Manual, Page 64Get this manual
Engine Idle Speed Adjustment 1The boat and engine must be in the water under normal operating conditions with the correct propeller installed The boat's movement must be unrestrainedThe boat must not be tied to dock or trailer2 Start the engine and allow it to reach normal operating temperature Check idle RPM in FORWARD gear with an accurate tachometer 11 71 1'-