1988-1992 Mercury Force 5HP Outboards Service Manual, Page 58Get this manual
345 Start motor and allow to warm up to operating temperatureMove throttle lever to "SHIFT" positionShift motor into "FORWARD" gear and turn idle needle clockwise (close) to the lowest "runnable" settingSlowly turn idle needle counterclockwiseuntil motor speed decreases and operation .becomes rough due to over-rich mixture(Note adjustment position Slowly turn idle needle clockwise: motor operation will become smooth and speed will increaseContinue turning idle needle clockwise until motor speed slows or misfires from too lean mixtureTurn idle needle to midpoint between settings noted in #6 and #7CORRECT ADJUSTMENT MIDPOINT