2003 YAMAHA WR 250F engine

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Page 392 of 860

YAMAHA WR 250F 2003  Owners Manual 4 - 67
ENGCAMSHAFTS
Fit the timing chain 
3 onto both
camshaft sprockets and install
the camshafts on the cylinder
head.
NOTE:The camshafts should be installed
onto the cylinder head so that the
punc

Page 398 of 860

YAMAHA WR 250F 2003  Owners Manual 4 - 73
ENGCYLINDER HEAD
CYLINDER HEAD
Extent of removal:
1 Cylinder head removal
Extent of removal Order Part name Q’ty Remarks
CYLINDER HEAD REMOVAL
Preparation for removal Seat and fuel tank Refer

Page 424 of 860

YAMAHA WR 250F 2003  Owners Manual 4 - 99
ENGVALVES AND VALVE SPRINGS
3. Install:
Valve cotter
NOTE:While compressing the valve spring
with a valve spring compressor 
1
install the valve cotters.
Valve spring 
compressor:
YM-4019/9089

Page 438 of 860

YAMAHA WR 250F 2003  Owners Manual 4 - 113
ENGCYLINDER AND PISTON
ASSEMBLY AND INSTALLATION
Piston ring and piston
1. Install:
Piston ring
Onto the piston.
NOTE:Be sure to install the piston rings
so that the manufacturer’s marks
o

Page 440 of 860

YAMAHA WR 250F 2003  Owners Manual 4 - 115
ENGCYLINDER AND PISTON
Cylinder
1. Lubricate:
Piston
Piston ring
Cylinder
NOTE:Apply a liberal coating of engine oil.
2. Install:
Dowel pin 
1 
O-ring 
2
NOTE:Apply the lithium soap base

Page 442 of 860

YAMAHA WR 250F 2003  Owners Manual 4 - 117
ENGCLUTCH
EC4A0000
CLUTCH
Extent of removal:
1 Push rod 1, 2 and push lever shaft removal
2 Push pod 1 disassembly
3 Friction plate and clutch plate removal
4 Primary driven gear removal
Exten

Page 454 of 860

YAMAHA WR 250F 2003  Owners Manual 4 - 129
ENGCLUTCH
EC4A5000ASSEMBLY AND INSTALLATION
Push lever shaft
1. Install:
Push lever shaft 
1 
Bolt (push lever shaft) 
2 
NOTE:Apply the lithium soap base grease
on the oil seal lip.
Apply

Page 456 of 860

YAMAHA WR 250F 2003  Owners Manual 4 - 131
ENGCLUTCH
4. Install:
Seat plate 
1 
Cushion spring 
2 
NOTE:Install the seat plate with its cham-
fered portion 
a facing the clutch
boss 
3.
Install the seat plate so that it is not
caug