Shibaura N843, Руководство по ремонту

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109823 2/09 3-3
d. Replace the valve if the clearance between the
stem and guide exceeds the service limit.
3. Valve seat
a. Since the valve seat is corrected according to the
valve guide, be sure to check the valve guide for
wear condition first before correcting the seat.
b. Correct the seat to the standard assembling values
of the contact width and recess using seat cutters
of 15°, 45° and 75°.
c. When the seat recess exceeds the service limit,
replace the cylinder head.
d. Coat the valve seat surface with compound and
lap the contact surface turning the valve.
e. Check that the valve contact surface is within the
standard value and the contact position is even.
f. When the cylinder head is replaced with a new
head, adjust the seat contact width and seat
recess to the specified values with a seat cutter
before lapping.
Clearance between valve stem and valve guide in(mm)
Intake valve Exhaust valve
Standard
assembling
value
Service limit Standard
assembling
value
Service limit
0.0012-
0.0024
(0.03–0.06)
More than
0.0079(0.2)
0.0016-
0.0030
(0.04-0.075)
More than
0.0100
(0.25)
Valve seat contact width in(mm)
Standard assembling value Repair value
In 0.059-0.083
(1.50-2.10)
More than
0.098(2.5)
Exhaust 0.063-0.071
(1.59-1.80)
More than
0.098(2.5)
Valve seat recess in(mm)
Standard assembling value Service limit
In,Ex 0.0335-0.0453
(0.85–1.15)
More than
0.0709(1.8)
Fig. 3-8
Clearance
Fig. 3-9
150°
90°
30°
Contact
Width
Fig. 3-10
Fig. 3-11
Recess
Valve
Lapper