Service Manual

2-12 PERIODIC MAINTENANCE
Periodic Maintenance Procedures
•
Holding the adjusting bolt with a spanner [A], tighten the
adjusting locknut [B] to the specified torque.
Torque - Valve Clearance Adjusting Locknuts: 11 N·m (1.1
kgf·m, 87 in·lb)
•
Do not overtighten the valve clearance adjusting locknuts.
•
After the valve clearance adjustment, measure the valve
clearance again. Readjust the valve clearance if neces-
sary.
Valve Seat Inspection
•
Remove the valve (see Valve Mechanism Removal/Instal-
lation in the Engine Top End chapter).
•
Inspect the valve seats for damage.
If the seats are warped or distorted beyond recondition-
ing, replace the cylinder head with a new one.
•
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.
Good [A]
TooWide[B]
Too Narrow [C]
Uneven [D]
If the valve seating pattern is not correct, repair the seat.
Valve Seating Surface Width (STD)
Exhaust
0.8 ∼ 1.6 mm (0.039 ∼ 0.059 in.)
Inlet
1.2 ∼ 1.8 mm (0.043 ∼ 0.067 in.)
Valve Seat Repair
•
Follow the manufacture’s instructions for use of valve seat
cutters.
Special Tools - Valve Seat Cutter Holder Bar: 57001-1128
Valve Seat Cutter Holder,
6: 57001-1360
Exhaust Valve
Valve Seat Cutter, 45° -
30: 57001-1187
Valve Seat Cutter, 32° -
33: 57001-1199
Inlet Valve
Valve Seat Cutter, 45° -
35: 57001-1116
Valve Seat Cutter, 32° -
35: 57001-1121
If the manufacture’s instructions are not available, use the
following procedure.