3-28 ENGINE
• Remove the oil seal with long-nose pliers.
• Remove the valve spring seat.
NOTE:
Removal of valves completes ordinary disassembling work. If
valve guides have to be removed for replacement after inspect-
ing the related parts, carry out the steps shown in the valve
guide servicing.
CYLINDER HEAD DISTORTION
• Decarbonize the combustion chamber.
Check the gasket surface of the cylinder head for distortion
using a straightedge and thickness gauge. Take clearance read-
ings at several places. If any clearance reading exceeds the ser-
vice limit, replace the cylinder head with a new one.
% Cylinder head distortion
Service Limit: 0.05 mm (0.002 in)
( 09900-20803: Thickness gauge
VALVE STEM RUNOUT
Support the valve with “V” blocks, as shown, and check its
runout with a dial gauge.
The valve must be replaced if the runout exceeds the limit.
% Valve stem runout
Service Limit: 0.05 mm (0.002 in)
( 09900-20701: Magnetic stand
09900-20607: Dial gauge (1/100 mm)
09900-21304: V-block
VALVE HEAD RADIAL RUNOUT
Place the dial gauge at right angles to the valve head face, and
measure the valve head radial runout.
If it exceeds limit, replace the valve.
% Valve head radial runout
Service Limit: 0.03 mm (0.001 in)
( 09900-20701: Magnetic stand
09900-20607: Dial gauge (1/100 mm)
09900-21304: V-block
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