4-10 ENGINE TOP END
Valves
Valve Clearance Adjustment
•
Loosen the valve adjusting screw locknut [A].
•
Turn the valve adjusting screw [B] until the correct clear-
ance is obtained.
•
Holding the adjusting screw with the holder [C], tighten
the locknut.
Special Tool - Valve Adjusting Screw Holder: 57001-1217
Torque - Valve Adjusting Screw Locknut: 9.8 N·m (1.0
kgf·m, 87 in·lb)
Valve Seat Inspection
•
Remove the valve.
•
Check the valve seating surface [A] between the valve [B]
and valve seat [C].
•
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.
•
Measure the outside diameter [D] of the seating pattern
on the valve seat.
If the outside diameter of the valve seating pattern is too
large or too small, repair the seat.
Valve Seating Surface Outside Diamete r
Inlet: 29.5 mm (1.16 in.)
Exhaust: 25.5 mm (1.00 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]
Too W ide [G]
Too Narrow [H]
Uneven [J]
If the width is too wide, too narrow or uneven, repair the
seat (See Valve Seat Repair).
Valve Seating Surface Width
Standard: 0.5 ∼ 1.1 mm (0.02 ∼ 0.04 in.)
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