Shibaura ST330, Workshop Manual

Page: 37 / 250

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➃ Replace the valve if the clearance between the stem and
guide exceeds the service limit.
113Y
(3) Valve seat
➀
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.
➁
Correct the seat to the standard assembling values of
the contact width and recess using seat cutters of 15°,
45° and 75°.
➂ When the seat recess exceeds the service limit, replace
the cylinder head.
Valve seat recess (mm)
Standard assembling value Service limit
0.85 – 1.15 1.8
114Y
115Y
Clearance between valve stem and valve guide (mm)
Intake valve Exhaust valve
Standard
assembling
value
Service
limit
Standard
assembling
value
Service
limit
0.03 – 0.06
More than
0.2
0.045 –
0.075
More
than 0.25
Valve seat contact width (mm)
Standard assembling value Repair value
Intake
1.66
－
1.87
2.5
Exhaust
1.66 － 1.73
2.5