Yamaha YZ426F(M)/LC Owner's Service Manual page 274

CAMSHAFTS
6. Remove:
Clips
Dowel pins
Exhaust camshaft 1
Intake camshaft 2
NOTE:
Attach a wire 3 to the timing chain to prevent
it from falling into the crankcase.
INSPECTION
Camshaft
1. Inspect:
Cam lobes
Pitting/scratches/blue discoloration →
Replace.
2. Measure:
Cam lobes length a and b
Out of specification → Replace.
Cam lobes length limit:
Intake:
a 31.6 mm (1.244 in)
b 22.85 mm (0.900 in)
Exhaust:
a 31.1 mm (1.224 in)
b 22.85 mm (0.900 in)
3. Measure:
Runout (camshaft)
Out of specification → Replace.
Runout (camshaft):
Less than 0.03 mm (0.0012 in)
4. Measure:
Camshaft-to-cap clearance
Out of specification → Measure bearing
diameter (camshaft)
Camshaft-to-cap clearance:
0.020 ~ 0.051 mm
(0.0008 ~ 0.0020 in)
4 - 20
ENG