ENGINE SYSTEMS
55
➃ Replace the valve if the clearance between the stem
and guide exceeds the service limit.
13
(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 contact width (mm)
Standard assembling value Repair value
1.7 – 2.1 More than 2.5
14
Valve seat recess (mm)
Standard assembling value Service limit
0.85 – 1.15 More than 1.8
15
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
Mora than
0.25
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