length YAMAHA WR 400F 2001 User Guide

2 - 31
SPECMAINTENANCE SPECIFICATIONS (WR400F)
Wheel:
Front wheel type Spoke wheel ----
Rear wheel type Spoke wheel ----
Front rim size/material 21 ´ 1.60/Aluminum ----
Rear rim size/material 18 ´ 2.15/Aluminum ----
Rim runout limit
Radial ---- 2.0 mm (0.08 in)
Lateral ---- 2.0 mm (0.08 in)
Drive chain:
Type/manufacturer DID520VM/DAIDO ----
Number of links 113 links + joint ----
Chain slack 40 ~ 50 mm (1.6 ~ 2.0 in) ----
Chain length (10 links) ----150.1 mm (5.91 in)
Front disc brake:
Disc outside diameter ´ Thickness 250 ´ 3.0 mm (9.84 ´ 0.12 in) 250 ´ 2.5 mm
(9.84 ´ 0.10 in)
Pad thickness 4.4 mm (0.17 in) 1 mm (0.04 in)
Master cylinder inside dia. 11.0 mm (0.433 in) ----
Caliper cylinder inside dia. 27.0 mm (1.063 in) ´ 2 ----
Brake fluid type DOT #4 ----
Rear disc brake:
Disc outside diameter ´ Thickness 240 ´ 4.0 mm (9.45 ´ 0.16 in) 240 ´ 3.5 mm
(9.45 ´ 0.14 in)
Deflection limit ----0.15 mm (0.006 in)
Pad thickness 6.4 mm (0.25 in) 1.0 mm (0.04 in)
Master cylinder inside dia. 12.7 mm (0.500 in) ----
Caliper cylinder inside dia. 27.0 mm (1.063 in) ´ 1 ----
Brake fluid type DOT #4 ----
Brake lever and brake pedal:
Brake lever position 95 mm (3.74 in) ----
Brake pedal height
(vertical height below footrest top)5 mm (0.20 in) ----
Clutch lever free play (at lever pivot) 2 ~ 4 mm (0.08 ~ 0.16 in) ----
Throttle grip free play 3 ~ 5 mm (0.12 ~ 0.20 in) ----Item Standard Limit

2 - 35
SPEC
EC220001
GENERAL TORQUE SPECIFICATIONS
This chart specifies torque for standard fasten-
ers with standard I.S.O. pitch threads. Torque
specifications for special components or
assemblies are included in the applicable sec-
tions of this book. To avoid warpage, tighten
multi-fastener assemblies in a crisscross fash-
ion, in progressive stages, until full torque is
reached. Unless otherwise specified, torque
specifications call for clean, dry threads. Com-
ponents should be at room temperature.
A: Distance between flats
B: Outside thread diameter
EC230000
DEFINITION OF UNITS
A
(Nut)B
(Bolt)TORQUE SPECIFICA-
TION
Nm m•kg ft•lb
10 mm
12 mm
14 mm
17 mm
19 mm
22 mm6 mm
8 mm
10 mm
12 mm
14 mm
16 mm6
15
30
55
85
1300.6
1.5
3.0
5.5
8.5
134.3
11
22
40
61
94
Unit Read Definition Measure
mm
cmmillimeter
centimeter10
-3 meter
10-2 meterLength
Length
kg kilogram 10
3 gram Weight
N Newton 1 kg ´ m/sec
2 Force
Nm
m • kgNewton meter
Meter kilogramN ´ m
m ´ kgTorque
Torque
Pa Pascal N/m
2Pressure
N/mm Newton per millimeter N/mm Spring rate
L
cm
3 Liter
Cubic centimeter—
—Volume or capacity
Volume or capacity
r/min Revolution per minute — Engine speed
GENERAL TORQUE SPECIFICATIONS/
DEFINITION OF UNITS

3 - 1
INSP
ADJ

MAINTENANCE INTERVALS
EC300000
REGULAR INSPECTION AND ADJUSTMENTS
MAINTENANCE INTERVALS
The following schedule is intended as a general guide to maintenance and lubrication. Bear in mind
that such factors as weather, terrain, geographical location, and individual usage will alter the
required maintenance and lubrication intervals. If you are a doubt as to what intervals to follow in
maintaining and lubricating your machine, consult your Yamaha dealer.
ItemAfter
break-inEvery
race
Every
third
or
500 km
(300 mi)Every
fifth
or
1,000 km
(600 mi)
As re-
quiredRemarks
ENGINE OIL
Replace
cc
OIL FILTER
Clean
cc
VALVES
Check the valve clearances.
Inspect
Replace
cc
c
c
The engine must be cold.
Check the valve seats and
valve stems for wear.
VALVE SPRINGS
Inspect
Replace
c
c
Check the free length and
the tilt.
VALVE LIFTERS
Inspect
Replace
c
c
Check for scratches and
wear.
CAMSHAFTS
Inspect
Replace
c
c
Inspect the camshaft sur-
face.
CAMSHAFT SPROCKETS
Inspect
Replace
c
c
Check for wear on the
teeth and for damage.
PISTON
Inspect
Clean
Replace
cc
c
c
Inspect crack
Remove carbon
PISTON RING
Inspect
Replace
c
cc
Check ring end gap
PISTON PIN
Inspect
Replace
c
c
CYLINDER HEAD
Inspect and clean
c
Remove carbon
Change gasket
CYLINDER
Inspect and clean
Replace
c
c
Inspect score marks
Inspect wear
CLUTCH
Inspect and adjust
Replace
cc
c
Inspect housing, friction
plate, clutch plate and
spring
TRANSMISSION
Inspect
Replace bearing
c
c


3

3 - 33
INSP
ADJ
SPROCKETS INSPECTION/DRIVE CHAIN INSPECTION
EC368000
SPROCKETS INSPECTION
1. Inspect:
lSprocket teeth a
Excessive wear ® Replace.
NOTE:
Replace the drive, driven sprockets and drive
chain as a set.
DRIVE CHAIN INSPECTION
1. Remove:
lMaster link clip
lJoint 1
lO-rings 2
lDrive chain 3
2. Clean:
lDrive chain
Place it in kerosene, and brush off as
much dirt as possible. Then remove the
chain from the kerosene and dry the
chain.
3. Measure:
lDrive chain length (10 links) a
Out of specification ® Replace.
Drive chain length (10 links):
Limit: 150.1 mm (5.91 in)
4. Check:
lDrive chain stiffness a
Clean and oil the chain and hold as
illustrated.
Stiff ® Replace drive chain.

3 - 39
INSP
ADJREAR SHOCK ABSORBER SPRING PRELOAD
ADJUSTMENT
EC36M013
REAR SHOCK ABSORBER SPRING
PRELOAD ADJUSTMENT
1. Elevate the rear wheel by placing the
suitable stand under the engine.
2. Remove:
lRear frame
3. Loosen:
lLocknut 1
4. Adjust:
lSpring preload
By turning the adjuster 2.
* For EUROPE
NOTE:
lBe sure to remove all dirt and mud from
around the locknut and adjuster before
adjustment.
lThe length of the spring (installed) changes
1.5 mm (0.06 in) per turn of the adjuster.
CAUTION:
Never attempt to turn the adjuster beyond
the maximum or minimum setting.
5. Tighten:
lLocknut
6. Install:
lRear frame Stiffer ® Increase the spring preload.
(Turn the adjuster 2 in.)
Softer ® Decrease the spring preload.
(Turn the adjuster 2 out.)
Spring length (installed) a:
Standard lengthExtent of adjustment
241 mm (9.49 in)
*244 mm (9.61 in)240.5 ~ 258.5 mm
(9.47 ~ 10.18 in)
T R..29 Nm (2.9 m · kg, 21 ft · lb)

4 - 24
ENGCAMSHAFTS
6. Remove:
lClips
lDowel pins
lExhaust camshaft 1
lIntake camshaft 2
NOTE:
Attach a wire 3 to the timing chain to prevent
it from falling into the crankcase.
INSPECTION
Camshaft
1. Inspect:
lCam lobes
Pitting/scratches/blue discoloration ®
Replace.
2. Measure:
lCam lobes length a and b
Out of specification ® Replace.
Cam lobes length:
Intake:
a31.7 ~ 31.8 mm
(1.2480 ~ 1.2520 in)
: 31.6 mm (1.244 in)
b22.95 ~ 23.05 mm
(0.9035 ~ 0.9075 in)
: 22.85 mm (0.900 in)
Exhaust:
a31.2 ~ 31.3 mm
(1.2283 ~ 1.2323 in)
: 31.1 mm (1.224 in)
b22.95 ~ 23.05 mm
(0.9035 ~ 0.9075 in)
: 22.85 mm (0.900 in)
3. Measure:
lRunout (camshaft)
Out of specification ® Replace.
Runout (camshaft):
Less than 0.03 mm (0.0012 in)

4 - 38
ENGVALVES AND VALVE SPRINGS
Valve spring
1. Measure:
lValve spring free length a
Out of specification ® Replace.
2. Measure:
lCompressed spring force a
Out of specification ® Replace.
bInstalled length
Free length (valve spring):
Intake:
41.36 mm (1.63 in)
: 39.3 mm (1.55 in)
Exhaust:
43.60 mm (1.72 in)
: 41.4 mm (1.63 in)
Compressed spring force:
Intake:
11.5 ~ 13.2 kg at 32.87 mm
(25.35 ~ 29.10 lb at 1.29 in)
Exhaust:
11.9 ~ 13.7 kg at 35.38 mm
(26.23 ~ 30.20 lb at 1.39 in)
3. Measure:
lSpring tilt a
Out of specification ® Replace.
Spring tilt limit:
Intake:
2.5Ëš/1.8 mm (0.071 in)
Exhaust:
2.5Ëš/1.9 mm (0.075 in)
Valve lifter
1. Inspect:
lValve lifter
Scratches/damage ® Replace both lift-
ers and cylinder head.

4 - 50
ENGCLUTCH (WR426F)
EC493000
REMOVAL POINTS
EC483211
Clutch boss
1. Remove:
lNut 1
lLock washer 2
lClutch boss 3
NOTE:
Straighten the lock washer tab and use the
clutch holding tool 4 to hold the clutch boss.
For USA and CDN
õExcept for USA and CDN
Clutch holding tool:
YM-91042/90890-04086

õ
EC494000
INSPECTION
EC484100
Clutch housing and boss
1. Inspect:
lClutch housing 1
Cracks/wear/damage ® Replace.
lClutch boss 2
Scoring/wear/damage ® Replace.
EC484201
Primary driven gear
1. Check:
lCircumferential play
Free play exists ® Replace.
lGear teeth a
Wear/damage ® Replace.
EC484400
Clutch spring
1. Measure:
lClutch spring free length a
Out of specification ® Replace springs
as a set.
Clutch spring free length:
Standard
48.4 mm (1.91 in) 47.4 mm (1.87 in)

4 - 57
ENGCLUTCH (WR400F)
EC493000
REMOVAL POINTS
EC483211
Clutch boss
1. Remove:
lNut 1
lLock washer 2
lClutch boss 3
NOTE:
Straighten the lock washer tab and use the
clutch holding tool 4 to hold the clutch boss.
For USA and CDN
õExcept for USA and CDN
Clutch holding tool:
YM-91042/90890-04086
õ
EC494000
INSPECTION
EC484100
Clutch housing and boss
1. Inspect:
lClutch housing 1
Cracks/wear/damage ® Replace.
lClutch boss 2
Scoring/wear/damage ® Replace.
EC484201
Primary driven gear
1. Check:
lCircumferential play
Free play exists ® Replace.
lGear teeth a
Wear/damage ® Replace.
EC484400
Clutch spring
1. Measure:
lClutch spring free length a
Out of specification ® Replace springs
as a set.
Clutch spring free length:
Standard
44 mm (1.73 in) 43 mm (1.69 in)

5 - 32
CHAS
EC554200
Base valve
1. Inspect:
lValve assembly 1
Wear/damage ® Replace.
lO-ring 2
Damage ® Replace.
EC554400
Fork spring
1. Measure:
lFork spring free length a
Out of specification ® Replace.
EC554502
Inner tube
1. Inspect:
lInner tube surface a
Score marks ® Repair or replace.
Use #1,000 grit wet sandpaper.
Damaged oil lock piece ® Replace.
lInner tube bends
Out of specification ® Replace.
Use the dial gauge 1.
NOTE:
The bending value is shown by one half of the
dial gauge reading.
WARNING
Do not attempt to straighten a bent inner
tube as this may dangerously weaken the
tube.
EC554600
Outer tube
1. Inspect:
lOuter tube 1
Score marks/wear/damage ® Replace.
Fork spring free length:
Standard
460 mm
(18.1 in)455 mm
(17.9 in)
Inner tube bending limit:
0.2 mm (0.008 in)
FRONT FORK