Checking The Valve Lifters; Installing The Valves - Yamaha YZ450FP 2023 Owner's Service Manual

EAM30094

CHECKING THE VALVE LIFTERS

1. Check:
• Valve lifter
Damage/scratches  Replace the valve lift-
ers and cylinder head.
EAM30095

INSTALLING THE VALVES

1. Clean:
• Valve stem end
2. Lubricate:
• Valve stem "1"
• Valve stem seal "2"
Recommended lubricant
Molybdenum disulfide oil
3. Install:
• Spring seat "1"
• Valve stem seal "2"
New
• Valve "3"
• Valve spring "4"
• Valve spring retainer "5"
VALVES AND VALVE SPRINGS
(to the cylinder head)
TIP
• Make sure each valve is installed in its original
place.
• Install the valve springs with the larger pitch "a"
facing up.
b. Smaller pitch
4. Install:
• Valve cotter "1"
TIP
Install the valve cotters by compressing the
valve spring with the valve spring compressor
"2" and the valve spring compressor attachment
"3".
Valve spring compressor
90890-04200
Valve spring compressor
YM-04019
Valve spring compressor attach-
ment
90890-04108
Valve spring compressor adapter
22 mm
YM-04108
1 1
5. To fasten the valve cotters onto the valve
stem, lightly tap the valve tip with a soft-face
hammer.
ECA13800
NOTICE
Hitting the valve tip with excessive force
5-28
2 2 2
3 3