Yamaha WR250FM service manual Valve spring

VALVES AND VALVE SPRINGS

ENG

Valve spring

1.Measure:

•Valve spring free length a

Out of specification → Replace.

Free length (valve spring):

Intake:

37.81mm (1.49 in) <Limit>: 35.9 mm (1.41 in)

Exhaust:

37.54mm (1.48 in) <Limit>: 35.7 mm (1.41 in)

2.Measure:

• Compressed spring force a

Out of specification → Replace.

b Installed length

Compressed spring force: Intake:

99 ~ 114 N at 29.13 mm

(9.9 ~ 11.4 kg at 29.13 mm,

22.27~ 25.57 lb at 1.15 in) Exhaust:

126 ~ 144 N at 29.30 mm

(12.6 ~ 14.4 kg at 29.30 mm,

28.44~ 32.41 lb at 1.15 in)

3.Measure:

•Spring tilt a

Out of specification → Replace.

Spring tilt limit: Intake:

2.5°/1.7 mm (0.067 in) Exhaust:

2.5°/1.6 mm (0.063 in)

Valve lifter

1.Inspect:

•Valve lifter

Scratches/damage → Replace both lift- ers and cylinder head.

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