1998-2006 Yamaha F20/F25 Outboards Service Manual, Page 75Get this manual
AND TILT (PTT) SYSTEM
2Adjust: Intake valve clearance Exhaust valve clearanceAdjusting steps: Turn the flywheel magneto and align mark CD on the driven sprocket with mark 11 6," on the cylinder block Loosen the locknut Adjust the valve adjusting screw 11 II
Turning in Turning out
Valve clearance is decreasedValve clearance is increased
Adjust the intake and exhaust valve clearances for cylinder #1 Turn the timing pulley 180 and align mark lie" on the driven sprocket 6" on the cylinder with mark block Adjust the intake and exhaust valve clearances for cylinder #2II