Checking The Timing Chain Tensioner; Installing The Cylinder Head - Yamaha XT250X 2008 Service Manual

2. Check:
Timing chain guide (exhaust side)
G
Crack/wear → Replace.
EAS24200

CHECKING THE TIMING CHAIN TENSIONER

1. Check:
Timing chain tensioner
G
Cracks/damage/rough movement → Re-
place.
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a. Lightly press the timing chain tensioner rod
into the timing chain tensioner housing by
hand.
NOTE:
While pressing the timing chain tensioner rod,
wind it clockwise with a thin screwdriver "1" until
it stops.
b. Remove the screwdriver and slowly release
the timing chain tensioner rod.
c. Make sure that the timing chain tensioner rod
comes out of the timing chain tensioner hous-
ing smoothly. If there is rough movement, re-
place the timing chain tensioner.
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EAS24230

INSTALLING THE CYLINDER HEAD

1. Install:
Cylinder head
G
Cylinder head bolts (226 mm)
G
Cylinder head bolts (45 mm)
G
Cylinder head bolt (226 mm)
22 Nm (2.2 m•kg, 16 ft•lb)
Cylinder head bolt (45 mm)
20 Nm (2.0 m•kg, 15 ft•lb)
NOTE:
Apply an engine oil to the seating face of cylin-
G
der head bolt (226-mm long), and apply a mo-
lybdenum disulfide oil to the bolt threads.
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5-10
CYLINDER HEAD
Tighten the cylinder head bolts in two stages in
G
the correct sequence as shown.
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2
2. Install:
Dowel pin
G
Camshaft sprocket
G
Timing chain
G
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
a. Make sure that generator rotor mark "a"
aligns with generator rotor cover mark "b". If
not, align them by turning the crankshaft
counterclockwise.
b. Align camshaft sprocket mark "c" with cylin-
der head mark "d".
c. Install the timing chain onto the camshaft
sprocket, and then install the camshaft
sprocket onto the camshaft.
NOTE:
When installing the camshaft sprocket, be sure
G
to keep the timing chain as tight as possible on
the exhaust side.
Align the dowel pin with the slot of camshaft
G
sprocket.
Assemble the camshaft sprocket by facing its
G
die stamp outward of the vehicle.
ECA13770
CAUTION:
Do not turn the crankshaft when installing
the camshaft sprockets to avoid damage or
improper valve.
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