Yamaha 2008 Raptor 250, Service Manual

Page: 127 / 311

ENG
4-11
CHECKING THE TIMING CHAIN GUIDES
The following procedure applies to the cam-
shaft 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:
• Camshaft sprocket
More than 1/4 tooth wear
→
Replace
the timing chain and camshaft sprocket and
crankshaft sprocket as a set.
1/4 tooth
Correct
Timing chain
Camshaft sprocket
3. Check:
• Timing chain guide (exhaust side)
CHECKING THE TIMING CHAIN
TENSIONERS
1. Check:
• Timing chain tensioner
Cracks/damage
→
Replace.
2. Check:
• One-way cam operation
Rough movement
→
Replace the timing
chain tensioner housing.
a. Lightly press the timing chain tensioner rod
into the timing chain tensioner housing by
hand.
NOTE: NOTE:
While pressing the timing chain tensioner rod,
wind it clockwise with a thin screwdriver
until it stops.
CYLINDER HEAD