
29
CHAPTER 3. ENGINE
Specified bore
7 mm
Fig. 3-29
(5) Inspection and correction of valve seats.
• Check for valve contacting width and depres-
sion.
When the contact width is wider than specified,
correct with a 75
°
valve seat cutter. When the
valve depression is more than specified, replace
the cylinder head assembly.
Standard value
Usable limit
Contact width
1.3 – 1.6 mm
2.0 mm
Valve depression
0.7 mm
1.4 mm
Valve guide
Cylinder head
7 mm
Contact
width
Subsidence
Fig. 3-30
• Apply polishing compound to the valve seat sur-
face and lap with the valve while tapping the
valve to secure sufficiently contact with the
whole circumference.
valve and valve guide as an assembly. Measure
the play at a point 10 mm apart above the valve
oil seal when the valve lift is 0 mm.
Fig. 3-27
(4) Replacement of the valve guide.
• Drive out the valve guide upwards from the cyl-
inder head bottom.
• Press in a new valve guide from the cylinder head
top, taking care not to damage the guide.
Fig. 3-28
Note:
Apply oil to the new valve guide ahead of time.
• Press in so that the distance from the cylinder
head top to the valve guide end becomes 7 mm.
• After installation, correct the bore diameter of
the valve guide to the specified value by reaming.
Содержание SCM49
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