2001 YAMAHA WR 426F engine

4 - 86
ENGCDI MAGNETO
4. Connect:
lCDI magneto lead
Refer to “CABLE ROUTING DIA-
GRAM” section in the CHAPTER 2.
5. Install:
lGasket [crankcase cover (left)]
lCrankcase cover (left) 1
lHose holder (cylinder head breather
hose) 2
lBolt [crankcase cover (left)]
NOTE:
Tighten the screws in stage, using a crisscross
pattern.
New
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
6. Install:
lShift pedal 1
lBolt (shift pedal)
NOTE:
When installing the shift pedal onto the shift
shaft, be sure that the center of the shift pedal
is about 2 mm a above the top of the footrest.
7. Install:
lEngine guard (left) 1
lHose holder (cylinder head breather
hose) 2
lBolt [engine guard (left)]
1
2
T R..23 Nm (2.3 m · kg, 17 ft · lb)

ENG
4 - 87
ENGINE REMOVAL
EC4M0000
ENGINE REMOVAL
Extent of removal Order Part name Q’ty Remarks
ENGINE REMOVAL
Preparation for removal Hold the machine by placing the
suitable stand under the frame.
WARNING
Support the machine securely so there is nodanger of it falling over.
Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Carburetor Refer to “CARBURETOR” section.
Exhaust pipe and silencer Refer to “EXHAUST PIPE AND
SILENCER” section.
Clutch cable Disconnect at engine side.
Decompression cable and guide Disconnect at engine side.
Radiator Refer to “RADIATOR” section.
Shift pedal Refer to “CDI MAGNETO” section.
Cylinder head breather hose and
oil tank breather hoseRefer to “CAMSHAFTS” section.
Drain the engine oil Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.
Spark plug cap
Disconnect the CDI magneto lead.

ENG
4 - 88
ENGINE REMOVAL
Extent of removal:1 Engine removal
Extent of removal Order Part name Q’ty Remarks
1 Engine skidplate 1
2 Neutral switch 1
3 Oil hose 2
4 Chain cover 1
Refer to “REMOVAL POINTS”. 5 Nut (drive sprocket) 1
6 Lock washer 1
7 Drive sprocket 1
8 Clip 1
9 Bolt (brake pedal) 1
10 Brake pedal 1
11 Engine upper bracket (right) 1
12 Engine upper bracket (left) 1
13 Engine lower bracket 2
14 Engine mounting bolt 3
15 Pivot shaft 1
Refer to “REMOVAL POINTS”.
16 Engine 1
1

4 - 89
ENGENGINE REMOVAL
EC4M3000
REMOVAL POINTS
EC4F3100
Drive sprocket
1. Remove:
lNut (drive sprocket) 1
lLock washer 2
NOTE:
lStraighten the lock washer tab.
lLoosen the nut while applying the rear brake.
2. Remove:
lDrive sprocket 1
lDrive chain 2
NOTE:
Remove the drive sprocket together with the
drive chain.
EC4M3301
Engine removal
1. Remove:
lPivot shaft 1
NOTE:
If the pivot shaft is pulled all the way out, the
swingarm will come loose. If possible, insert a
shaft of similar diameter into the other side of
the swingarm to support it.
2. Remove:
lEngine 1
From right side.
NOTE:
Make sure that the couplers, hoses and cables
are disconnected.

4 - 90
ENGENGINE REMOVAL
EC4M5000
ASSEMBLY AND INSTALLATION
EC4M5160
Engine installation
1. Install:
lEngine 1
Install the engine from right side.
lPivot shaft 2
lEngine mounting bolt (lower) 3
lEngine lower bracket 4
lBolt (engine bracket) 5
lEngine mounting bolt (front) 6
lEngine upper bracket (right) 7
lEngine upper bracket (left) 8
lBolt (engine bracket) 9
lEngine mounting bolt (upper) 0
EC4M5211
Brake pedal
1. Install:
lSpring
lBrake pedal 1
lO-ring 2
lBolt (brake pedal) 3
lClip 4
NOTE:
lApply the lithium soap base grease on the
bolt, O-rings and brake pedal bracket.
lInstall the clip with its stopper portion a fac-
ing inward.
T R..85 Nm (8.5 m · kg, 61 ft · lb)
T R..69 Nm (6.9 m · kg, 50 ft · lb)
T R..34 Nm (3.4 m · kg, 24 ft · lb)
T R..69 Nm (6.9 m · kg, 50 ft · lb)
T R..34 Nm (3.4 m · kg, 24 ft · lb)
T R..55 Nm (5.5 m · kg, 40 ft · lb)
New
T R..26 Nm (2.6 m · kg, 19 ft · lb)
EC4M5331
Drive sprocket
1. Install:
lDrive sprocket 1
lDrive chain 2
NOTE:
Install the drive sprocket together with the
drive chain.

4 - 91
ENGENGINE REMOVAL
2. Install:
lLock washer 1
lNut (drive sprocket) 2
NOTE:
Tighten the nut while applying the rear brake.
New
T R..75 Nm (7.5 m · kg, 54 ft · lb)
3. Bend the lock washer tab to lock the nut.
4. Install:
lChain guide
lChain cover 1
lScrew (chain cover) 2
T R..8 Nm (0.8 m · kg, 5.8 ft · lb)
5. Install:
lOil hose 1
lBolt (oil hose) 2
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
6. Install:
lSpring 1
lPin 2
lO-ring 3
lNeutral switch 4
lBolt (neutral switch) 5
NOTE:
Apply the lithium soap base grease on the O-
ring.
New
T R..4 Nm (0.4 m · kg, 2.9 ft · lb)

ENG
4 - 92
CRANKCASE AND CRANKSHAFT
CRANKCASE AND CRANKSHAFT
CRANKCASE AND CRANKSHAFT
Extent of removal:1 Crankcase separation2 Crankshaft removal
Extent of removal Order Part name Q’ty Remarks
CRANKCASE SEPARATION
Preparation for removal Engine Refer to “ENGINE REMOVAL” section.
Piston Refer to “CYLINDER AND PISTON” sec-
tion.
Balancer Refer to “BALANCER” section.
Kick axle assembly
Refer to “KICK AXLE AND SHIFT
SHAFT” section.
Segment
Stator Refer to “CDI MAGNETO” section.
1 Timing chain guide (rear) 1
2 Timing chain 1
3 Bolt (40 mm) 3
Refer to “REMOVAL POINTS”. 4 Bolt (50 mm) 4
5 Bolt (60 mm) 2
6 Bolt (75 mm) 3
7 Hose guide 1
8 Clutch cable holder 1
9 Crankcase (right) 1
10 Crankcase (left) 1
21

4 - 95
ENGCRANKCASE AND CRANKSHAFT
REMOVAL POINTS
Crankcase
1. Separate:
lCrankcase (right)
lCrankcase (left)
Separation steps:
lRemove the crankcase bolts, hose guide
and clutch cable holder.
NOTE:
Loosen each bolt 1/4 of a turn at a time and
after all the bolts are loosened, remove
them.
lRemove the crankcase (right).
NOTE:
lPlace the crankcase with its left side
downward and split it by inserting a screw-
driver tip into the splitting slit a in the
crankcase.
lLift the crankcase (right) horizontally while
lightly patting the case splitting slit and
engine mounting boss using a soft ham-
mer, and leave the crankshaft and trans-
mission with the crankcase (left).
CAUTION:
Use soft hammer to tap on the case half.
Tap only on reinforced portions of case.
Do not tap on gasket mating surface.
Work slowly and carefully. Make sure the
case halves separate evenly. If one end
“hangs up”, take pressure off the push
screw, realign, and start over. If the
cases do not separate, check for a
remaining case screw or fitting. Do not
force.
lRemove the dowel pins and O-ring.
a