Checking The Camshaft - Yamaha WR250F 2022 Owner's Service Manual

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EAM30081

CHECKING THE CAMSHAFT

1. Check:
• Camshaft lobe
Blue discoloration/pitting/scratches  Re-
place the camshaft.
2. Measure:
• Camshaft lobe dimensions "A"
Out of specification  Replace the camshaft.
Camshaft lobe dimensions
Lobe height limit (Intake)
32.130 mm (1.2650 in)
Lobe height limit (Exhaust)
33.460 mm (1.3173 in)
3. Measure:
• Camshaft-journal-to-camshaft-cap clearance
Out of specification  Measure the camshaft
journal diameter.
Camshaft-journal-to-camshaft-
cap clearance
0.028–0.062 mm (0.0011–0.0024
in)
a. Install the camshaft into the cylinder head.
b. Position a strip of Plastigauge® "1" onto
the camshaft journal as shown.
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c. Install the dowel pins and the camshaft
caps.
TIP
• Tighten the camshaft cap bolts in a crisscross
pattern from innermost to outer caps.
• Do not turn the camshaft when measuring the
camshaft journal-to-camshaft cap clearance.
d. Remove the camshaft caps and then mea-
sure the width of the Plastigauge® "1".
4. Measure:
• Camshaft journal diameter "a"
Out of specification  Replace the camshaft.
Within specification  Replace the cylinder
head and the camshaft caps as a set.
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CAMSHAFT
Camshaft cap bolt
10 N·m (1.0 kgf·m, 7.4 lb·ft)
Camshaft journal diameter
21.959–21.972 mm (0.8645–
0.8650 in)
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