Checking The Valves And Valve Guides - Yamaha MIO Service Manual

VALVES AND VALVE SPRINGS
3. Remove:
NOTE:
_
Identify the position of each part very carefully
so that it can be reinstalled in its original place.
EAS00239
CHECKING THE VALVES AND VALVE
GUIDES
The following procedure applies to all of the
valves and valve guides.
1. Measure:
4 - 25
• upper spring seat 1
• valve spring 2
• valve stem seal 3
• lower spring seat 4
• valve 5
• valve-stem-to-valve-guide clearance
Valve-stem-to-valve-guide clearance =
Valve guide inside diameter a –
Valve stem diameter b
Out of specification → Replace the valve
guide.
Valve-stem-to-valve-guide clear-
ance
Intake
0.015 ~ 0.042 mm
(0.0006 ~ 0.0017 in)
<Limit>: 0.080 mm (0.0031 in)
Exhaust
0.030 ~ 0.057 mm
(0.0012 ~ 0.0022 in)
<Limit>: 0.110 mm (0.0043 in)
ENG