Measure the outside diameter [D] of the seating pattern on the valve seat.
If the outside diameter is too large or too small, repair the seat (see Valve Seat Repair).
Valve Seating Surface Outside Diameter Standard:
Exhaust 23.9 
24.1 mm (0.941
0.949 in.)
Intake 30.4 
30.6 mm (1.197
1.205 in.)
Measure the seat width [E] of the portion where there is no build-up carbon (white portion) of the valve seat with a vernier caliper.
Good [F]
If the width is too wide [G], too narrow [H] or uneven [J], repair the seat (see Valve Seat Repair).
Valve Seating Surface Width Standard:
Exhaust 0.8 
1.2 mm (0.03
0.05 in.)
Intake 0.5 
1.0 mm (0.02
0.04 in.)
Valve-to-Guide Clearance Measurement (Wobble Method)
Valve Seat RepairExhaust Pipe Removal
Remove:
Radiator (see Radiator and Radiator Fan Removal in the
Cooling System chapter)
Exhaust Pipe Clamp Bolt [A] (Loosen)
Remove the exhaust pipe holder nuts [A], and pull out the
exhaust pipe [B] forward from the premuffler chamber.
...
Parts Removal/Installation
WARNINGGasoline is extremely flammable and can be
explosive
under certain conditions. Turn the ignition
switch OFF. Do not smoke. Make sure the area is
well-ventilated and free from any source of flame
or sparks; this includes any appliance with a pilot
light.
NOTICE
...
Special Tools and Sealants
Outside Circlip Pliers:
57001-144
Piston Pin Puller Assembly:
57001-910
Piston Ring Compressor Grip:
57001-1095
Piston Ring Compressor Belt, 67
79:
57001-1097
Bearing Driver Set:
57001-1129
Liquid Gasket, TB1216B:
92104-1064
Liquid Gasket, TB1207B:
92104-2068
...