Service Manual

PERIODIC MAINTENANCE 2-9
Periodic Maintenance Procedures
Valve Seat Inspection
•
Remove the valve (see Engine Top End chapter).
•
Inspect the valve seats for damage.
If the seats are warped or distorted beyond reconditioning, replace
the cylinder head.
•
Pitted or worn valve seats can be refaced. Lap the valves to the seats
after refacing.
•
Coat the valve seat with machinist’s dye.
•
Push the valve into the guide.
•
Rotate the valve against the seat with a lapping tool.
•
Pull the valve out, and check the seating pattern on the valve head.
It must be the correct width [A] and even all the way around.
NOTE

The valve stem and guide must be in good condition or this check
will not be valid.
If the valve seating pattern is not correct, repair the seat.
Valve Seating Surface Width (STD)
Inlet, Exhaust 0.6 ~ 0.9 mm (0.024 ~ 0.035 in.)
Valve Seat Repair
•
Follow the manufacturer’s instructions for use of valve seat cutters.
Special Tools
Intake Valve:
Seat Cutter 45

- 27.5 57001-1114
Outside Cutter 32

-
28.0 57001-1119
Exhaust Valve:
Seat Cutter 45

-
27.5 57001-1114
Outside Cutter 32

- 25.0 57001-1118
Valve Seat Cutter Holder-
6.0: 57001-1360
Valve Seat Cutter Holder Bar: 57001-1128
If the manufacturer’s instructions are not available, use the following
procedure.
Seat Cutter Operating Cares:
1. This valve seat cutter is designed only for valve seat repair.
Therefore the cutter must not be used for other purposes.
2. Do not drop or hit the valve seat cutter, or the diamond particles
may fall off.
3. Do not fail to apply engine oil to the valve seat cutter before
grinding the seat surface. Also wash off ground particles sticking
to the cutter with washing oil.
NOTE

Do not use a wire brush to remove the metal particles from the
cutter. It will take off the diamond particles.
4. Setting the valve seat cutter holder [A] in position, operate the
cutter [B] with one hand [C]. Do not apply too much force to the
diamond portion.
NOTE

Prior to grinding, apply oil to the cutter, and during the operation
wash off any ground particles sticking to the cutter with washing
oil.
5. After use wash the cutter with washing oil and apply a thin layer
of engine oil before storing.