Suzuki DF 2.5 Service Manual page 80

6-14 POWER UNIT
Valve stem end
Inspect the valve stem end face for pitting and wear. If pitting or
wear is found, the valve stem end may be resurfaced.
If the chamfer of stem end has been worn away, replace the
valve.
Valve stem runout
Measure the valve stem runout.
 09900-20602: Dial gauge
09900-20701: Magnetic stand
09900-21304: "V" block set
Valve stem runout:
Service limit: 0.05 mm (0.002 in)
If the measurement exceeds the service limit, replace the valve.
Valve head radial runout
Measure the valve head radial runout.
 09900-20602: Dial gauge
09900-20701: Magnetic stand
09900-21304: "V" block set
Valve head radial runout:
Service limit: 0.08 mm (0.003 in)
If the measurement exceeds the service limit, replace the valve.
Valve head thickness
Measure the thickness T of the valve head.
 09900-20101: Vernier calipers
Valve head thickness:
Service limit: IN. & EX. 0.5 mm (0.02 in)
If the measurement exceeds the service limit, replace the valve.
45˚