Yamaha RS90K Manuel D'atelier page 486

VALVES AND VALVE SPRINGS
13. Measure:
• Valve spring tilt a
Out of specification → Replace the valve
spring.
14. Inspect:
• Valve lifter
Damage/scratches → Replace the valve lift-
ers and cylinder head.
INSTALLATION
1. Deburr:
• Valve stem end
(with an oil stone)
2. Lubricate:
• Valve stem 1
• Valve stem seal 2
(with the recommended lubricant)
5-34
ENG
Maximum valve spring tilt:
2.5°/1.7 mm (0.07 in)
Recommended lubricant:
Molybdenum disulfide oil