10. Cylinder Block/Head
142
• Valve stem play
4. Install the valve on the cylinder head valve guide.
5. Use a special service tool to check whether the valve
seat is aligned with the center.
Inspecting the Valve Seat
1. Amount of contact with mating surface
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1) To check the amount of wear on the valve seat, measure
the height of the mating surface between the intake and
exhaust valve.
2) If the measurement exceeds the allowable limit, replace
the part.
3) Install the valve on the cylinder head valve seat.
4) Use a dial gauge to measure the insertion length of the
valve from the bottom of the cylinder head.
• Valve step height
• Valve angle
5) If the insertion length of the valve exceeds the allowable
limit, replace the valve seat.
6) To remove the valve seat, perform arc welding in two
places on the valve seat; then, use a special service tool
to pull out the valve seat.
Note) The inside diameter needs to be bored during the
removal of the valve seat.
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7) Before assembling the valve seat, cool it in dry ice for
approx. two hours.
8) Use a bench press to press-fit the valve seat into the
cylinder head.
9) Apply abrasive to the valve head mating surface of the
valve seat.
10) Turn the valve to polish the valve seat surface until the
valve is properly seated. Then, remove the abrasive
completely.
Reference value Allowable limit
Intake Valve
0.038 ~ 0.067 mm
(0.0014 ~ 0.0026 in.)
0.10 mm
(0.0039 in.)
Exhaust Valve
0.051 ~ 0.080 mm
(0.002 ~ 0.0032 in.)
0.15 mm
(0.0059 in.)
Reference value Allowable limit
Intake valve
(A)
0.9 ~ 1.1 mm
(0.0354 ~ 0.0433 in.)
1.3 mm
(0.0512 in.)
Exhaust valve
(A)
0.9 ~ 1.1 mm
(0.0354 ~ 0.0433 in.)
1.6 mm
(0.063 in.)
Intake valve (B) Exhaust valve (B)
60° 45°
Cylinder head
Valve seat
Weld bead
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