Rato R80, Maintenance Manual, Page: 60 / 79

Part IV Disassembly and Maintenance
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c) Grind the valve seat by 45° grinder to create a smooth valve seat being concentric with the
valve guide, rotate it clockwise and not it is not allowed to rotate counterclockwise.
Tool: valve grinder
d) Use 32° and 45° grinders to reduce and adjust the valve seat, to make it be in contact with
middle part of valve cone face.
•
Grind top edge of valve seat by 32° grinder (contacting too high).
•
Grind bottom edge of the valve by 45° grinder (contacting too low).
Make sure that the contact width of valve seat completed is within specified range.
Valve seat
grinding
handle
Intake valve: 32
°
Exhaust valve: 32
°
Intake valve: 45
°
Exhaust valve: 45
°