Yamaha RS90K Manuel D'atelier page 476

VALVES AND VALVE SPRINGS
REMOVAL
The following procedure applies to all of the valves
and related components.
NOTE:
Before removing the internal parts of the cylinder
head (e.g., valves, valve springs, valve seats),
make sure the valves properly seal.
NOTE:
Make a note of the position of each valve lifter and
valve pad so that they can be reinstalled in their
original place.
NOTE:
There should be no leakage at the valve seat 1.
NOTE:
2
Remove the valve cotters by compressing the valve
spring with the valve spring compressor set 2 and
attachment 3.
3
1
5-29
1. Remove:
• Valve lifter 1
• Valve pad 2
2. Inspect:
• Valve
(for leakage)
Leakage at the valve seat → Check the valve
face, valve seat, and valve seat width.
Inspection steps:
• Pour a clean solvent a into the intake and
exhaust ports.
• Check that the valves properly seal.
3. Remove:
• Valve cotters 1
Valve spring compressor set:
90890-04019, YM-04019
Attachment:
90890-04108, YM-04108
ENG