Yamaha YZ250F(W) Owner's Service Manual page 314

CAMSHAFTS
Decompression system
1. Check:
• Decompression system
Checking steps:
• Check that the decompression mecha-
nism cam 1 moves smoothly.
• Check that the decompression mecha-
nism cam lever pin 2 projects from the
camshaft.
Timing chain tensioner
1. Check:
• While pressing the tensioner rod lightly
with fingers, use a thin screwdriver 1
and wind the tensioner rod up fully clock-
wise.
• When releasing the screwdriver by press-
ing lightly with fingers, make sure that the
tensioner rod will come out smoothly.
• If not, replace the tensioner assembly.
ASSEMBLY AND INSTALLATION
Camshaft
1. Install:
• Exhaust camshaft 1
• Intake camshaft 2
Installation steps:
• Turn the crankshaft counterclockwise with
a wrench.
NOTE:
• Apply the molybdenum disulfide oil on the
camshafts.
• Apply the engine oil on the decompression
system.
• Squeezing
allows the crankshaft to be turned easily.
• Align the T.D.C. mark a on the rotor with
the align mark b on the crankcase cover
when piston is at T.D.C. on compression
stroke.
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ENG
the decompression lever