2001-2002 Yamaha 50HP F50Z/T50Z Ouboard 4-stroke engines service manual, Page 165Get this manual
Cylinder head 4Use 60 cutter to adjust the contact width of the bottom edge of the valve seat7If the valve seat contact area is too narrow and situated near the top edge of the valve face, use 30 cutter to cut the top edge of the valve seatIf necessary, use 45 cutter to center the area and set its width
S62Y5461
E Previous contact width 5Use 45 cutter to adjust the contact width of the valve seat to specificationS62Y5470
E Previous contact width 8If the valve seat contact area is too narrow and situated near the bottom edge of the valve face, use 60 cutter to cut the bottom edge of the valve seatIf necessary, use 45 cutter to center the area and set its width