Check the cylinder head for warpage with a straight edge and feeler gauge.
Service limit: 0.10 mm (0.004 in).

Valve spring
Measure the free length of the valve springs.
Service limits:
- IN: 41.9 mm (1.65 in)
- EX: 42.4 mm (1.67 in)

Cam chain tensioner/cam chain guide
Inspect the cam chain tensioner and guide for excessive wear or damage, replace if necessary.

Valve/valve guide
Inspect each valve for bends, burns, scratches or abnormal wear.
Insert the valves in their original positions in the cylinder head. Check that each valve moves up and down smoothly, without binding.

Measure the each valve stem O.D. and record it.
Service limits:
- IN: 6.57 mm (0.259 in)
- EX: 7.94 mm (0.313 in)
Ream the valve guide to remove any carbon build-up before measuring the guide.
Insert the reamer from the combustion chamber side of the head and rotate the reamer clockwise.
Tools:
- IN: Valve guide reamer, 6.6 mm 07984-657010D
- EX: Valve guide reamer, 8 mm 07ZMH-MCHA200

Measure the valve guide I.D. and record it.
Service limits:
- IN: 6.635 mm (2.612 in)
- EX: 8.055 mm (0.3171 in)
Subtract each valve stem O.D. from the corresponding guide I.D. to obtain the stem-to-guide clearance.

Service limits:
- IN: 0.08 mm (0.003 in)
- EX: 0.12 mm (0.005 in)
If the stem-to-guide clearance exceeds the service limit, determine if a new guide with standard dimensions would bring the clearance within tolerance.
If so, replace any guides as necessary and ream to fit. If the stem-to-guide clearance exceeds the service limit with a new guide, also replace the valve.
Inspect and reface the valve seats whenever the valve guides are replaced (see below).