2001-2002 Yamaha 50HP F50Z/T50Z Ouboard 4-stroke engines service manual, Page 162Get this manual
IpOWRIIfriJ: IPower unit 2Measure the valve margin thickness Replace if out of specification
Valve stem runout: Intake: 0.03 mm (0.0012 in) Exhaust: 0.03 mm (0.0012 in)
Checking the valve guides
-S62Y5320
Measure the valve guide inside diameter Replace if out of specification
Valve margin thicknessIntake: 0.6-1.0 mm (0.024-0.039 in) Exhaust: 0.7-1.1 mm (0.028-0.043 in) 3Measure the valve stem diameter (6)Replace if out of specificationS62Y5350
Valve guide inside diameter limit5.50-5.51 mm (0.2165-0.2169 in)