Checking The Valve Lifters; Installing The Valves - Yamaha YZF-R25 Service Manual

2. Measure:
• Compressed valve spring force "a"
Out of specification → Replace the valve
spring.
Installed compression spring
force (intake)
159.60–183.60 N (16.27–18.72
kgf, 35.88–41.27 lbf)
Installed compression spring
force (exhaust)
159.60–183.60 N (16.27–18.72
kgf, 35.88–41.27 lbf)
Installed length (intake)
30.90 mm (1.22 in)
Installed length (exhaust)
30.90 mm (1.22 in)
b. Installed length
3. Measure:
• Valve spring tilt "a"
Out of specification → Replace the valve
spring.
Spring tilt (intake)
1.6 mm (0.06 in)
Spring tilt (exhaust)
1.6 mm (0.06 in)
VALVES AND VALVE SPRINGS
EAS30287

CHECKING THE VALVE LIFTERS

The following procedure applies to all of the
valve lifters.
1. Check:
• Valve lifter
Damage/scratches → Replace the valve lift-
ers and cylinder head.
EAS30288

INSTALLING THE VALVES

The following procedure applies to all of the
valves and related components.
1. Deburr:
• Valve stem end
(with an oil stone)
2. Lubricate:
• Valve stem "1"
• Valve stem end
(with the recommended lubricant)
Recommended lubricant
Molybdenum disulfide oil
3. Lubricate:
• Valve stem seal "2"
(with the recommended lubricant)
Recommended lubricant
Engine oil
5-31