Suzuki drz 400E Service Manual page 65

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 us-
ing 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.
09900-20803: Thickness gauge
Cylinder head distortion
Service Limit: 0.05 mm (0.002 in)
VALVE STEM RUNOUT
Support the valve using V-blocks and measure the valve stem
runout using the dial gauge, as shown. If the runout exceeds the
service limit, replace the valve with a new one.
09900-20606: Dial gauge (1/100 mm)
09900-20701: Magnetic stand
09900-21304: V-block set (100 mm)
Valve stem runout
Service Limit: 0.05 mm (0.002 in)
ENGINE 3-23