Installing The Valves - Yamaha YFM70RY Service Manual

2. Measure:
• Compressed valve spring force "a"
Out of specification → Replace the valve
spring.
b. Installed length
Installed compression spring
force (intake)
169.00–199.00 N (17.23–20.29
kgf, 37.99–44.73 lbf)
Installed compression spring
force (exhaust)
169.00–199.00 N (17.23–20.29
kgf, 37.99–44.73 lbf)
Installed length (intake)
35.00 mm (1.38 in)
Installed length (exhaust)
35.00 mm (1.38 in)
3. Measure:
• Valve spring tilt "a"
Out of specification → Replace the valve
spring.
Spring tilt (intake)
2.5°/1.70 mm
Spring tilt (exhaust)
2.5°/1.70 mm
VALVES AND VALVE SPRINGS
EAS24340

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 seal "2"
(with the recommended lubricant)
Recommended lubricant
Molybdenum disulfide oil
3. Install:
• Valve spring seat "1"
• Valve stem seal "2"
• Valve "3"
• Valve spring "4"
• Valve spring retainer "5"
(into the cylinder head)
5-24
New