steering YAMAHA WR 426F 2002 User Guide

3 - 4
INSP
ADJ
PRE-OPERATION INSPECTION AND MAINTENANCE
EC320000
PRE-OPERATION INSPECTION AND MAINTENANCE
Before riding for break-in operation, practice or a race, make sure the machine is in good operating
condition.
Before using this machine, check the following points.
GENERAL INSPECTION AND MAINTENANCE
Item Routine Page
CoolantCheck that coolant is filled up to the radiator filler cap.
Check that the coolant level is correct in the coolant reservoir
tank.
Check the cooling system for leakage.P.3-5 ~ 9
FuelCheck that a fresh gasoline is filled in the fuel tank. Check the
fuel line for leakage.P.1-14
Engine oilCheck that the oil level is correct. Check the crankcase and
frame oil line for leakage.P.3-14 ~ 18
Gear shifter and clutchCheck that gears can be shifted correctly in order and that the
clutch operates smoothly.P.3-10
Throttle grip/HousingCheck that the throttle grip operation and free play are correctly
adjusted. Lubricate the throttle grip and housing, if necessary.P.3-10 ~ 11
Brakes Check the play of front brake and effect of front and rear brake. P.3-26 ~ 32
ChainCheck chain slack and alignment. Check that the chain is lubri-
cated properly.P.3-33 ~ 36
WheelsCheck for excessive wear and tire pressure. Check for loose
spokes and have no excessive play.P.3-44 ~ 45
SteeringCheck that the handlebar can be turned smoothly and have no
excessive play.P.3-45 ~ 46
Front forks and rear shock
absorberCheck that they operate smoothly and there is no oil leakage. P.3-36 ~ 43
Cables (wires)Check that the clutch and throttle cables move smoothly. Check
that they are not caught when the handlebars are turned or
when the front forks travel up and down.—
Muffler Check that the muffler is tightly mounted and has no cracks.—
Sprocket Check that the driven sprocket tightening bolt is not loose. P.3-33
Lubrication Check for smooth operation. Lubricate if necessary. P.3-47
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P.1-19
Lead connectorsCheck that the CDI magneto, CDI unit, and ignition coil are con-
nected tightly.P.1-6
SettingsIs the machine set suitably for the condition of the racing course
and weather or by taking into account the results of test runs
before racing? Are inspection and maintenance completely
done?P.7-1 ~ 22

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INSP
ADJ
STEERING HEAD INSPECTION AND ADJUSTMENT
2. Inspect:
Bearing free play
Exist play → Replace.
STEERING HEAD INSPECTION AND
ADJUSTMENT
1. Elevate the front wheel by placing a suit-
able stand under the engine.
2. Check:
Steering shaft
Grasp the bottom of the forks and gen-
tly rock the fork assembly back and
forth.
Free play → Adjust steering head.
3. Check:
Steering smooth action
Turn the handlebar lock to lock.
Unsmooth action → Adjust steering ring
nut.
4. Adjust:
Steering ring nut
Steering ring nut adjustment steps:
Remove the headlight.
Remove the handlebar and handle crown.
Loosen the ring nut 1 using the ring nut
wrench 2.
Ring nut wrench:
YU-33975/90890-01403

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INSP
ADJ
STEERING HEAD INSPECTION AND ADJUSTMENT
Tighten the ring nut 3 using ring nut
wrench 4.
NOTE:
Set the torque wrench to the ring nut wrench
so that they form a right angle.
Ring nut wrench:
YU-33975/90890-01403
T R..
Ring nut (initial tightening):
38 Nm (3.8 m • kg, 27 ft • lb)
Loosen the ring nut one turn.
Retighten the ring nut using the ring nut
wrench.
WARNING
Avoid over-tightening.
T R..
Ring nut (final tightening):
7 Nm (0.7 m • kg, 5.1 ft • lb)
Check the steering shaft by turning it lock
to lock. If there is any binding, remove the
steering shaft assembly and inspect the
steering bearings.
Install the handle crown 5, steering shaft
nut 6, handlebar 7, handlebar holder 8
and headlight 9.
NOTE:
The upper handlebar holder should be
installed with the punched mark a for-
ward.
Insert the end of fuel breather hose 0 into
the hole of the steering shaft.
CAUTION:
First tighten the bolts on the front side of
the handlebar holder, and then tighten
the bolts on the rear side.
T R..
Steering shaft nut:
145 Nm (14.5 m • kg, 105 ft • lb)
Handlebar upper holder:
28 Nm (2.8 m • kg, 20 ft • lb)
Pinch bolt (handle crown):
23 Nm (2.3 m • kg, 17 ft • lb)
Headlight:
7 Nm (0.7 m • kg, 5.1 ft • lb)

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CHAS

12. Adjust:

Clutch lever free play
Refer to “CLUTCH ADJUSTMENT”
section in the CHAPTER 3.

Decompression lever free play
Refer to “DECOMPRESSION LEVER
ADJUSTMENT” section in the CHAP-
TER 3.
13. Fasten the decompression cable
1
and
clutch cable
2
with a clamp
3
.
1
2
3

14. Insert the end of the fuel breather hose
1
into the hole of the steering shaft.
HANDLEBAR

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CHAS
EC560000
STEERING
Extent of removal:1 Under bracket removal2 Bearing removal
Extent of removal Order Part name Q’ty Remarks
STEERING REMOVAL
WARNING
Support the machine securely so there is no
danger of it falling over.
Preparation for removal Hold the machine by placing the
suitable stand under the engine.
Headlight
Handlebar
Cable guide
Front fenderRefer to “HANDLEBAR” section.
1 Trip meter 1
2 Steering shaft nut 1
3 Front fork 2 Refer to “FRONT FORK” section.
4 Handle crown 1
5 Ring nut 1 Use special tool.
Refer to “REMOVAL POINTS”.
6 Under bracket 1
7Ball race cover
1
2
1
STEERING

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CHASSTEERING
Extent of removal Order Part name Q’ty Remarks
8 Bearing (upper) 1
9 Bearing (lower) 1 Refer to “REMOVAL POINTS”.
10Ball race
2Refer to “REMOVAL POINTS”.
2

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CHAS
EC563000
REMOVAL POINTS
EC563202
Ring nut
1. Remove:
Ring nut 1
Use the ring nut wrench 2.
WARNING
Support the steering shaft so that it may
not fall down.
Ring nut wrench:
YU-33975/90890-01403
EC563300
Bearing (lower)
1. Remove:
Bearing (lower) 1
Use the floor chisel 2.
CAUTION:
Take care not to damage the steering shaft
thread.
EC563400
Ball race
1. Remove:
Ball race 1
Remove the ball race using long rod 2
and the hammer.
EC564000
INSPECTION
EC564200
Steering shaft
1. Inspect:
Steering shaft 1
Bend/damage → Replace.
STEERING

5 - 50
CHASSTEERING
EC564101
Bearing and ball race
1. Wash the bearings and ball races with a
solvent.
2. Inspect:
Bearing 1
Ball race
Pitting/damage → Replace bearings
and ball races as a set.
Install the bearing in the ball races.
Spin the bearings by hand. If the bear-
ings hang up or are not smooth in their
operation in the ball races, replace
bearings and ball races as a set.
EC565000
ASSEMBLY AND INSTALLATION
Under bracket
1. Install:
Bearing (lower) 1
NOTE:
Apply the lithium soap base grease on the dust
seal lip and bearing inner circumference.
2. Install:
Ball race
Bearing (upper) 1
Ball race cover 2
NOTE:
Apply the lithium soap base grease on the
bearing and ball race cover lip.
3. Install:
Under bracket 1
NOTE:
Apply the lithium soap base grease on the
bearing and the portion a of the steering
shaft.

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CHAS

4. Install:

Plain washer
1


Ring nut
2

Tighten the ring nut using the ring nut
wrench
3
.
Refer to “STEERING HEAD INSPEC-
TION AND ADJUSTMENT” section in
the CHAPTER 3.
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)

5. Check the steering shaft by turning it lock
to lock. If there is any binding, remove
the steering shaft assembly and inspect
the steering bearings.
6. Install:

Plain washer
1

7. Install:

Front fork
1


Handle crown
2

NOTE:


Temporarily tighten the pinch bolts (under
bracket).

Do not tighten the pinch bolts (handle crown)
yet.
8. Install:

Plain washer
1


Steering shaft nut
2

T R..145 Nm (14.5 m · kg, 105 ft · lb)

STEERING

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CHASSTEERING
9. After tightening the nut, check the steer-
ing for smooth movement. If not, adjust
the steering by loosening the ring nut little
by little.
10. Adjust:
Front fork top end a
Front fork top end (standard) a:
Zero mm (Zero in)
11. Tighten:
Pinch bolt (handle crown) 1
Pinch bolt (under bracket) 2
CAUTION:
Tighten the under bracket to specified
torque. If torqued too much, it may cause
the front fork to malfunction.
T R..23 Nm (2.3 m · kg, 17 ft · lb)
T R..20 Nm (2.0 m · kg, 14 ft · lb)
12. Install:
Trip meter 1 1