Checking The Timing Chain, Crankshaft Sprocket And Timing Chain Guide - Yamaha YFM250RX 2008 Service Manual

CRANKSHAFT ASSEMBLY
2. Measure:
• Big end side clearance
Out of specification → Replace the big end
bearing, crankshaft pin, or connecting rod.
Big end side clearance D
3. Measure:
• Crankshaft width
Out of specification → Replace the crank-
shaft.
Width A
4. Check:
• Crankshaft sprocket
Damage/wear → Replace the crankshaft.
• Bearing
Cracks/damage/wear
crankshaft.
5. Check:
• Crankshaft journal oil passage
Obstruction → Blow out with compressed
air.
CHECKING THE TIMING CHAIN,
CRANKSHAFT SPROCKET AND TIMING
CHAIN GUIDE
The following procedure applies to all of the
camshaft sprockets and timing chain guides.
1. Check:
• Timing chain
Damage/stiffness → Replace the timing
chain and camshaft sprocket and crank-
shaft sprocket as a set.
2. Check:
• Crankshaft sprocket
More than 1/4 tooth wear
the timing chain and camshaft sprocket and
crankshaft sprocket as a set.
1/4 tooth
Correct
Timing chain roller
Crankshaft sprocket
4-74
ENG
0.350 ~ 0.650 mm
(0.0138 ~ 0.0256 in)
69.25 ~ 69.30 mm
(2.726 ~ 2.728 in)
→
Replace the
→ Replace