Yamaha YZ 2018 Series Owner's Service Manual page 211

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EASB29B212
CHECKING THE CAMSHAFT
1. Check:
• Camshaft lobes
Blue discoloration/pitting/scratches  Re-
place the camshaft.
2. Measure:
• Camshaft lobe dimensions "A"
Out of specification  Replace the cam-
shaft.
Camshaft lobe dimensions
Lobe height (Intake)
31.830–31.930 mm (1.2531–
1.2571 in)
Limit
31.730 mm (1.2492 in)
Lobe height (Exhaust)
33.870–33.970 mm (1.3335–
1.3374 in)
Limit
33.770 mm (1.3295 in)
3. Measure:
• Camshaft runout
Out of specification  Replace.
Camshaft runout limit
0.030 mm (0.0012 in)
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4. Measure:
• Camshaft-journal-to-camshaft-cap clear-
ance
Out of specification  Measure the cam-
shaft journal diameter.
Camshaft-journal-to-camshaft-
cap clearance
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a. Install the camshaft into the cylinder head.
b. Position a strip of Plastigauge® "1" onto the
camshaft journal as shown.
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.
5-14
CAMSHAFT
0.028–0.062 mm (0.0011–0.0024
in)
Camshaft cap bolts
10 N·m (1.0 kgf·m, 7.4 lb·ft)
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