5. Inspection and servicing of basic engine parts
111
(4) Valve guide
1) Measuring inside diameter of valve guide.
Measure the inside diameter of the valve guide and replace it if it exceeds the wear limit.
NOTE: The inside diameter standard dimensions assume a pressure fit.
2) Replacing the valve guide
Use the insertion tool and tap in the guide with a
mallet.
The intake valve guide and exhaust valve guide
are of different dimensions.
3) Valve guide projection
a) Put liquid nitrogen or ether (or alcohol) with dry
ice added in a container and put the valve guide
for replacement in it for cooling. Then insert it in
with a valve guide inserting tool.
Do not touch the cooled valve guide with bare hands
to avoid skin damage.
b) Check the inside diameter and finish to the
standard inside diameter as required with a
reamer.
Check the projection from the seat surface of the valve
spring.
mm
Standard
Limit
Valve guide
inside dia.
Intake
6.000-6.012
6.08
Exhaust
6.000-6.012
6.08
Clearance
Intake
0.025-0.052
0.16
Exhaust
0.040-0.067
0.17
Valve guide projection (mm)
9.8-10.0
Tool
Valve guide
Tool
Valve guide
Cylinder head
Stem seal
Valve guide
Stem seal projection
Valve guide projection
Clearance
Summary of Contents for 3YM20
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