2006 YAMAHA YZ250LC engine oil

3-27
FRONT FORK OIL SEAL AND DUST SEAL CLEANING/
FRONT FORK INTERNAL PRESSURE RELIEVING/
FRONT FORK REBOUND DAMPING FORCE ADJUSTMENTINSP
ADJ
EC36D001
FRONT FORK OIL SEAL AND DUST SEAL
CLEANING
1. Remove:
9Protector
9Dust seal 1
NOTE:
Use a thin screw driver, and be careful not to
damage the inner fork tube and dust seal.
2. Clean:
9Dust seal a
9Oil seal b
NOTE:
9Clean the dust seal and oil seal after every run.
9Apply the lithium soap base grease on the in-
ner tube.
EC36H002
FRONT FORK REBOUND DAMPING FORCE
ADJUSTMENT
1. Adjust:
9Rebound damping force
By turning the adjuster 1.
Stiffer a a
Increase the rebound damping
force. (Turn the adjuster 1 1
in.)
Softer b b
Decrease the rebound
damping force. (Turn the
adjuster 1 1
out.)
EC36f000
FRONT FORK INTERNAL PRESSURE
RELIEVING
NOTE:
If the front fork initial movement feels stiff during
a run, relieve the front fork internal pressure.
1. Elevate the front wheel by placing a suitable
stand under the engine.
2. Remove the air bleed screw 1and release
the internal pressure from the front fork.
3. Install:
9Air bleed screw
1 Nm (0.1 m•kg, 0.7 ft•lb)
1P8-9-31-3B 5/13/05 11:44 AM Page 18

2. Install:
9Gasket (reed valve) 1
9Plate (reed valve) 2
9Reed valve assembly 3
9Reed valve spacer 4
NOTE:
Install the reed valve spacer with its chamfered
side ato the right.
4-13
ENGCARBURETOR AND REED VALVE
10 Nm (1.0 m•kg, 7.2 ft•lb)
3. Install:
9Carburetor joint 1
9Bolt (carburetor joint) 2
EC4652F0
Carburetor
1. Install:
9Power jet 1
To carburetor 2.
2. Install:
9O-ring 1
9Solenoid valve 2
To carburetor.
cC
9Before installing the solenoid valve, blow air
on the solenoid valve and its installing loca-
tion on the carburetor in order to remove
any foreign particles such as chips etc.
9Apply the engine oil on the solenoid valve
thread.
1P8-9-31-4A 5/12/05 1:18 PM Page 26

4-29
CYLINDER HEAD, CYLINDER AND PISTONENG
7. Install:
9O-ring 1
9Side holder 2
9Screw (side holder) 3
9YPVS breather hose 4
NOTE:
9Apply the lithium soap base grease on the O-
rings.
9Install the side holder with its projection a
facing upward.
8. Install:
9Gasket (power valve cover) 1
9Power valve cover 2
9Screw (power valve cover) 3
NOTE:
9Install the gasket with its cut afacing down-
ward and the seal print side toward the power
valve cover.
9Install the power valve cover so that the arrow
mark bfaces upward.
EC475233
Piston ring and piston
1. Install:
9Piston ring 1
NOTE:
9Take care not to scratch the piston or damage
the piston ring.
9Align the piston ring gap with the pin 2.
9After installing the piston ring, check the
smooth movement of it.
2. Install:
9Gasket (cylinder) 1
9Small end bearing 2
9Dowel pin 3
NOTE:
9Apply the engine oil onto the bearing (crank-
shaft and connecting rod) and connecting rod
big end washers.
9Install the gasket with the seal print side toward
the crankcase.
4 Nm (0.4 m•kg, 2.9 ft•lb)
4 Nm (0.4 m•kg, 2.9 ft•lb)
1P8-9-31-4B 4/29/05 3:07 PM Page 4

4-30
CYLINDER HEAD, CYLINDER AND PISTONENG
EC475383
Cylinder head and cylinder
1. Apply:
9Engine oil
To piston 1piston ring 2and cylinder sur-
face.
2. Install:
9Cylinder 1
cC
Make sure the piston rings are properly
positioned. Install the cylinder with one
hand while compressing the piston rings
with the other hand.
NOTE:
After installing, check the smooth movement of
the piston.
3. Install:
9Nut (cylinder) 1
NOTE:
Tighten the nuts in stage, using a crisscross pat-
tern.
3. Install:
9Piston 1
9Piston pin 2
9Piston pin clip 3
NOTE:
9The arrow aon the piston dome must point to
exhaust side.
9Before installing the piston pin clip, cover the
crankcase with a clean rag to prevent the pis-
ton pin clip from falling into the crankcase cavi-
ty.
cC
Do not allow the clip open ends to meet the
piston pin slot b b
.
42 Nm (4.2 m•kg, 30 ft•lb)
1P8-9-31-4B 4/29/05 3:07 PM Page 6

4-33
CLUTCH AND PRIMARY DRIVEN GEARENG
Extent of removal Order Part name Q’ty Remarks
CLUTCH PLATE AND
FRICTION PLATE REMOVAL
Preparation for Drain the transmission oil.
Refer to “TRANSMISSION OIL REPLACE-
removalMENT” section in the CHAPTER 3.
Bolt (brake pedal) Shift the brake pedal downward.
Rotor and stator Refer to
“CDI MAGNETO”section.
Clutch cable Disconnect at engine side.
1 Clutch cover 1
2 Screw (clutch spring) 6
3 Clutch spring 6
4 Pressure plate 1
5 Friction plate 8
6 Clutch plate 7
Extent of removal:1Clutch plate and friction plate removal
EC490000
CLUTCH AND PRIMARY DRIVEN GEAREC498000
CLUTCH PLATE AND FRICTION PLATE
1
10 Nm (1.0 m•kg, 7.2 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
1P8-9-31-4B 4/29/05 3:07 PM Page 12

Extent of removal Order Part name Q’ty Remarks
ENGINE REMOVAL
Preparation for
Hold the machine by placing the
removalsuitable stand under the engine.
Drain the transmission oil. Refer to “TRANSMISSION OIL
REPLACEMENT” section in the
CHAPTER 3.
Seat and fuel tankRefer to “SEAT, FUEL TANK AND
SIDE COVERS” section.
CarburetorRefer to “CARBURETOR AND REED
VALVE” section.
Exhaust pipe and silencer Refer to “EXHAUST PIPE AND
Exhaust pipe stay (rear) SILENCER” section.
Clutch cable Disconnect at engine side.
Radiator Refer to “RADIATOR” section.
Spark plug
Disconnect the CDI magneto lead.
4-60
ENGINE REMOVALENG
EC4M0000
ENGINE REMOVAL
w
Support the machine securely so there is no dan-
ger of it falling over.



26 Nm (2.6 m•kg, 19 ft•lb)
64 Nm (6.4 m•kg, 46 ft•lb)
75 Nm (7.5 m•kg, 54 ft•lb)
5 Nm (0.5 m•kg, 3.6 ft•lb)
34 Nm (3.4 m•kg, 24 ft•lb)
64 Nm (6.4 m•kg, 46 ft•lb)
85 Nm (8.5 m•kg, 61 ft•lb)
åExcept for USA and CDN
4 Nm (0.4 m•kg, 2.9 ft•lb)
1P8-9-31-4C 5/12/05 1:20 PM Page 22

4-65
CRANKCASE AND CRANKSHAFTENG
EC4N0000
CRANKCASE AND CRANKSHAFT
Extent of removal:1Crankcase separation2Crankshaft removal
3Crankshaft bearing removal
10 Nm (1.0 m•kg, 7.2 ft•lb)30 Nm (3.0 m•kg, 22 ft•lb)
14 Nm (1.4 m•kg, 10 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
Extent of removal Order Part name Q’ty Remarks
CRANKCASE AND CRANKSHAFT
REMOVAL
Preparation for Engine Refer to “ENGINE REMOVAL”section.
removal Piston Refer to “
CYLINDER HEAD, CYLINDER
AND PISTON
” section.
Primary drive gear
Kick idle gearRefer to “
KICK AXLE, SHIFT SHAFT AND
Stopper leverPRIMARY DRIVE GEAR”section.
Rotor and stator Refer to “CDI MAGNETO” section.
1 Segment 1 Refer to “REMOVAL POINTS”.
2 Holder 2
Except for USA and CDN
3 Bolt (Neutral switch lead holder) 1
4 Bolt [L=50 mm (1.97 in)] 7
5 Bolt [L=60 mm (2.36 in)] 1
6 Bolt [L=70 mm (2.76 in)] 3
7 Holder 2
8 Crankcase (right) 1 Use special tool.
9 Crankcase (left) 1 Refer to “REMOVAL POINTS”.
10 Crankshaft 1 Use special tool.
Refer to “REMOVAL POINTS”.
11 Oil seal 2
12 Bearing 2 Refer to “REMOVAL POINTS”.




12
3






1P8-9-31-4C 5/12/05 1:20 PM Page 32

6. Install:
9Holder (except for USA and CDN) 1
9Bolt [holder (except for USA and CDN)] 2
9Bolt (crankcase)
NOTE:
Tighten the crankcase tightening bolts in stage,
using a crisscross pattern.
4-71
CRANKCASE AND CRANKSHAFTENG
8. Tighten:
9Segment 1
9Bolt (segment) 2
NOTE:
9When installing the segment onto the shift cam
3, align the punch mark awith the dowel pin
b.
9Turn the segment clockwise until it stops and
tighten the bolt.
cC
If the segment gets an impact, it may be
damaged. Take care not to give an impact
to the segment when tightening the bolt.
30 Nm (3.0 m•kg, 22 ft•lb)
7. Install:
9Tension spring 1
9Holder 2
9Bolt (holder) 3
NOTE:
Install the holder so that it contacts the projec-
tion aon the crankcase (right).
10 Nm (1.0 m•kg, 7.2 ft•lb)
9. Remove:
9Sealant
Forced out on the cylinder mating surface.
10. Apply:
9Engine oil
To the crank pin, bearing, oil delivery hole
and connecting rod big end washer.
11. Check:
9Crankshaft and transmission operation
Unsmooth operation
Repair.
14 Nm (1.4 m•kg, 10 ft•lb)
14 Nm (1.4 m•kg, 10 ft•lb)
1P8-9-31-4C 5/12/05 1:21 PM Page 44