Checking The Valves And Valve Guides - Yamaha 2004 YP400 Service Manual

VALVES AND VALVE SPRINGS
4. 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:
5 - 23
• 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
0.010 ~ 0.037 mm
(0.0004 ~ 0.0015 in)
<Limit>: 0.080 mm (0.0032 in)
Exhaust
0.025 ~ 0.052 mm
(0.0010 ~ 0.0020 in)
<Limit>: 0.100 mm (0.0039 in)
ENG