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If the ID of valve guide pipe is below the standard or exceeds the maintenance limit, replace
cylinder head.
Standard
Maintenance limit
6.6-6.615 mm
6.662 mm
Reamer:
When reaming preciously valve guide with a
reamer, be sure to be at room temperature to get
good result.
a)
Apply a layer of cutting grease to the valve
reamer and valve guide.
b)
Screw into the reamer clockwise until the
reamer is fully screwed into the air valve
guide pipe.
c)
Continue to rotate clockwise to pull out the
valve reamer from the valve guide.
Tool: valve guide reamer
d)
Thoroughly remove dirt and debris from cylinder cover.
e)
Inspect the hole of valve guide pipe, which shall be in the center of valve guide pipe and
shall be straight and unobstructed, and insert the valve to inspect whether the action is
smooth. If not, the valve guide may have been bent during assembly. If it is bent or
damaged, replace the valve.
f)
Check the clearance between valve stem and the guide.
g)
Clearance between the valve stem and the valve guide pipe: Subtract OD of valve stem from
corresponding ID of valve guide pipe to obtain the clearance between valve guide pipe and valve
stem.
h)
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:
Correct
Wrong
