Cylinder Head Flaw; Valve Recessing; Valve Lapping - Kubota KX080-3 Workshop Manual

WSM KX080-3 Service

Cylinder Head Flaw

1. Prepare an air spray red check.
2. Clean the surface of the cylinder head with the detergent (2).
3. Spray the cylinder head surface with the red permeative liquid
(1). Leave it five to ten minutes after spraying.
4. Wash away the red permeative liquid on the cylinder head
surface with the detergent (2).
5. Spray the cylinder head surface with the white developer (3).
6. If flawed, it can be identified as red marks.
(1) Red Permeative Liquid
(2) Detergent

Valve Recessing

1. Clean the cylinder head, the valve face and seat.
2. Insert the valve into the valve guide.
3. Measure the valve recessing with a depth gauge.
4. If the measurement exceeds the allowable limit, replace the
valve.
If it still exceeds the allowable limit after replacing the valve,
replace the cylinder head.
Factory
spec.
Valve recessing
Allowable
limit
(1) Cylinder Head Surface

Valve Lapping

1. Apply compound evenly to the valve lapping surface.
2. Insert the valve into the valve guide. Lap the valve onto its seat
with a valve flapper or screwdriver.
3. After lapping the valve, wash the compound away and apply oil,
then repeat valve lapping with oil.
4. Apply prussian blue to the contact surface to check the seated
rate. If it is less than 70 %, repeat valve lapping again.
IMPORTANT
• When valve lapping is performed, be sure to check the valve
recessing and adjust the valve clearance after assembling
the valve.
(1) Correct
(2) Incorrect
III-S-147
(3) White Developer
W1076542
(recessing)
Intake
0.6 to 0.8 mm
valve
0.0236 to 0.0315 in.
(recessing)
Exhaust
0.85 to 1.05 mm
valve
0.0335 to 0.0413 in.
(recessing)
1.2 mm
0.0472 in.
(A) Recessing
(B) Protrusion
W1061543
(3) Incorrect
W1061709
Engine