1996 Mercury Force 25 HP Service Manual 90-830894 895, Page 26Get this manual
6Slowly turn idle mixture screw counterclockwise until motor speed decreases and operation becomes rough due to over-rich mixtureNote screw position aLeanRichCorrect Adjustment
7Slowly turn idle mixture screw clockwise: motor operation will become smooth and speed will increaseContinue turning idle mixture screw clockwise until motor speed slows or misfires from too lean mixtureNote screw positionSTurn idle mixture screw to midpoint between settings noted in steps and 7