2001-2002 Yamaha 50HP F50Z/T50Z Ouboard 4-stroke engines service manual, Page 163Get this manual
Cylinder head 2Install the new valve guide by striking the special service tool from the camshaft side until the valve guide clip contacts the cylinder head4Measure the valve guide inside diameterReplace the valve guide if out of specification
Valve guide inside diameter: 5.50-5.51 mm (0.2165-0.2169 in)
Checking the valve seat
1Eliminate carbon deposits from the valve with scraperApply thin, even layer of Mechanic's blueing dye (Oykem) onto the valve seatLap the valve slowly on the valve seat with valve lapper (commercially obtainable) as shown3
S62Y5370