ENGINE
SM-E4B SERIES, WSM
1-S54
Correcting Valve and Valve Seat
• Before correcting the valve and seat, check the valve stem
and the I.D. of valve guide section, and repair them if
necessary.
• After correcting the valve seat, be sure to check the valve
recessing.
1) Correcting Valve
1. Correct the valve with a valve refacer.
2) Correcting Valve Seat
1. Slightly correct the seat surface with a 0.79 rad (45 °) valve seat
cutter.
2. Fitting the valve, check the contact position of the valve face
and seat surface with prussian blue. (Visual check) [If the valve
has been used for a long period, the seat tends to come in
contact with the upper side of the valve face.]
3. Grind the upper surface of the seat with a 0.26 rad (15 °) valve
seat cutter until the valve seat touches to the center of the valve
face (so that (1) equals (2) as shown in the figure).
4. Grind the seat with a 0.79 rad (45 °) valve seat cutter again, and
visually recheck the contact between the valve and seat.
5. Repeat steps 3 and 4 until the correct contact is achieved.
6. Continue lapping until the seated rate becomes more than 70 %
of the total contact area.
9Y1210785ENS0068US0
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.
• When valve lapping is performed, be sure to check the
valve recessing and adjust the valve clearance after
assembling the valve.
9Y1210785ENS0069US0
Valve face angle Factory specification
0.79 rad
45 °
Valve seat angle Factory specification
0.79 rad
45 °
(1) Valve Seat Width
(2) Identical Dimensions
(A) Check Contact
(B) Correct Seat Width
(C) Check Seat Surface
(D) Check Contact
(a) 0.26 rad (15 °)
(b) 0.79 rad (45 °)
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