Yamaha YZ 2019 Series, Owner'S Service Manual

Page: 213 / 398

CAMSHAFT
5-14
from falling into the crankcase.
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.
3. Measure:
• Camshaft runout
Out of specification

Replace.
4. Measure:
• Camshaft-journal-to-camshaft-cap clearance
Out of specification

Measure the camshaft
journal diameter.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
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.
d. Remove the camshaft caps and then mea-
sure the width of the Plastigauge® “1”.
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)
Camshaft runout limit
0.030 mm (0.0012 in)
1 2
3
Camshaft-journal-to-camshaft-
cap clearance
0.028–0.062 mm (0.0011–0.0024
in)
Camshaft cap bolt
10 N·m (1.0 kgf·m, 7.4 lb·ft)
1
T
R
.
.