Yamaha WR250F 2021 - Checking the Camshaft

CAMSHAFT
5-17
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-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”.
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.
Camshaft lobe dimensions
Lobe height limit (Intake)
32.130 mm (1.2650 in)
Lobe height limit (Exhaust)
33.750 mm (1.3287 in)
Camshaft-journal-to-camshaft-
cap clearance
0.028–0.062 mm (0.0011–0.0024
in)
2
2
2
1
1
3
3
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)
1
1
1
T
R
.
.
1
1
1