Yamaha MX250 - Removing the Valves and Valve Springs; Checking the Valves and Valve Springs

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ENGINE
VALVE
REMOVING THE VALVES AND VALVE SPRINGS
The following procedure applies to all of the valves, valve
springs and related components.
1.
Remove:
• Valve cotter “1”
• Valve spring retainer “2”
• Valve spring “3”
•Valve “4”
• Valve stem seal (Intake side only)
Remove the parts using the valve spring compres-
sor “5”.
CHECKING THE VALVES AND VALVE SPRINGS
The following procedure applies to all of the valves, valve
springs and related components.
1.
Measure:
• Valve stem length “a”
• Valve head diameter “b”
Out of specifications  Replace.
5
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4
Do not compress the valve spring more than neces-
sary.
Valve spring compressor:
90890-01253
NOTICE
b
a
Valve stem length (Intake):
90.0 mm (3.5433 in)
Valve stem length (Exhaust):
90.3 mm (3.5551 in)
Valve head diameter (Intake):
31.9–32.1 mm (1.2559–1.2638 in)
Valve head diameter (Exhaust):
28.9–29.1 mm (1.1377–1.1456 in)