1986+ Mercury 6/8/9.9/10/15HP 2-stroke Factory Service Manual, Page 102Get this manual

TIMING, SYNCHRONIZINGADJUSTING
Fast Idle Adjustment
1Push primerfast idle knob completely in and rotate knob fully COUNTERCLOCKWISE2Shift outboard to NEUTRAL3Adjust screw to remove all clearance between idle wire and trigger

• ATV
• Jet Ski
• Outboard Motors
• Personal Watercraft
• Snowmobiles
• Stern Drives