Rato R80, Maintenance Manual, Page: 59 / 79

Part IV Disassembly and Maintenance
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e) Clearance between the valve stem and the valve guide pipe: Subtract outer diameter of
valve stem from corresponding inner diameter of valve guide pipe to obtain the clearance
between valve guide pipe and valve stem.
f) If the clearance between valve stem and valve guide exceeds maintenance limit, replace a
new guide, to judge if the clearance can be within maintenance limit. If so, replace valve guide
and stick valve guide. Re-trim valve seat when replacing the valve guide pipe.
④
Valve seat:
a) Thoroughly remove carbon deposit out of combustion chamber and valve seat, and apply a
thin layer of red lead powder on the surface of valve, or other adhesive color paints easy to be
wiped.
b) Insert the valve and press the valve with effort a few times, but do not rotate the valve on
the valve seat. If the valve seat is stained with paint, it indicates that it is in close contact with
the valve; otherwise, it fails to contact. This indicates that the valve and the valve seat are not
concentric.
Correct
Incorrect
Valve surface