Page 10 of 786

EC050000
TO THE NEW OWNER
This manual will provide you with a good basic
understanding of features, operation, and
basic maintenance and inspection items of this
machine. Please read this manual carefully
and completely before operating your new
machine. If you have any questions regarding
the operation or maintenance of your machine,
please consult your Yamaha dealer.
NOTE:
This manual should be considered a perma-
nent part of this machine and should remain
with it even if the machine is subsequently
sold.
EC060000
NOTICE
Some data in this manual may become out-
dated due to improvements made to this
model in the future. If there is any question
you have regarding this manual or your
machine, please consult your Yamaha
dealer.
EC070001
F.I.M. MACHINE WEIGHTS:
Weights of machines without fuel
The minimum weights for motocross
machines are:
for the class 125 cc ....................... minimum
88 kg (194 lb)
for the class 250 cc ....................... minimum
98 kg (216 lb)
for the class 500 cc ....................... minimum
102 kg (225 lb)
In modifying your machine (e.g., for weight
reduction), take note of the above limits of
weight.
Page 16 of 786

ILLUSTRATED SYMBOLS
(Refer to the illustration)
Illustrated symbols 1 to 7 are designed as
thumb tabs to indicate the chapter’s number
and content.
1General information
2Specifications
3Regular inspection and adjustments
4Engine
5Chassis
6Electrical
7Tuning
Illustrated symbols 8 to D are used to identify
the specifications appearing in the text.
8With engine mounted
9Special tool
0Filling fluid
ALubricant
BTightening
CSpecified value, Service limit
DResistance (
Ω), Voltage (V), Electric current (A)
Illustrated symbols E to H in the exploded
diagrams indicate grade of lubricant and loca-
tion of lubrication point.
EApply engine oil
FApply molybdenum disulfide oil
GApply lightweight lithium-soap base grease
HApply molybdenum disulfide grease
Illustrated symbols I to J in the exploded
diagrams indicate where to apply a locking
agent and where to install new parts.
IApply locking agent (LOCTITE®)
JUse new one 12
34
56
78
90
AB
CD
EF
GH
IJ
GEN
INFOSPEC
INSP
ADJ
ENG
CHAS–+ELEC
TUN
T R..
EM
BM
New
Page 32 of 786

1 - 4
GEN
INFO
IMPORTANT INFORMATION
EC132000
ALL REPLACEMENT PARTS
1. We recommend to use Yamaha genuine
parts for all replacements. Use oil and/or
grease recommended by Yamaha for
assembly and adjustment.
EC133000
GASKETS, OIL SEALS AND O-RINGS
1. All gaskets, oil seals, and O-rings should
be replaced when an engine is overhauled.
All gasket surfaces, oil seal lips, and O-
rings must be cleaned.
2. Properly oil all mating parts and bearings
during reassembly. Apply grease to the oil
seal lips.
EC134000
LOCK WASHERS/PLATES AND COTTER
PINS
1. All lock washers/plates 1 and cotter pins
must be replaced when they are removed.
Lock tab(s) should be bent along the bolt or
nut flat(s) after the bolt or nut has been
properly tightened.
EC135001
BEARINGS AND OIL SEALS
1. Install the bearing(s) 1 and oil seal(s) 2
with their manufacturer’s marks or numbers
facing outward. (In other words, the
stamped letters must be on the side
exposed to view.) When installing oil
seal(s), apply a light coating of light-weight
lithium base grease to the seal lip(s). Oil
the bearings liberally when installing.
CAUTION:
Do not use compressed air to spin the
bearings dry. This causes damage to the
bearing surfaces.
Page 90 of 786

SPEC
2 - 1
EC200000
SPECIFICATIONS
EC211000
GENERAL SPECIFICATIONS
Model name: WR450FV (USA, CDN, AUS, NZ)
WR450F (EUROPE, ZA)
Model code number: 5TJB (USA)
5TJC (EUROPE)
5TJD (CDN, AUS, NZ, ZA)
Dimensions: USA, ZA, CDN EUROPE, AUS, NZ
Overall length 2,200 mm (86.61 in) 2,195 mm (86.42 in)
Overall width 830 mm (32.68 in)←
Overall height 1,295 mm (50.98 in)←
Seat height 985 mm (38.78 in) 990 mm (38.98 in)
Wheelbase 1,490 mm (58.66 in)←
Minimum ground clearance 370 mm (14.57 in)←
Dry weight:
Without oil and fuel 113.0 kg (249.1 lb)
Engine:
Engine type Liquid cooled 4-stroke, DOHC
Cylinder arrangement Single cylinder, forward inclined
Displacement 449 cm
3 (15.8 Imp oz, 15.2 US oz)
Bore × stroke 95.0 × 63.4 mm (3.74 × 2.50 in)
Compression ratio 12.3 : 1
Starting system Kick and electric starter
Lubrication system: Dry sump
Oil type or grade:
Engine oil (For USA and CDN)
At 5 °C (40 °F) or higher È
Yamalube 4 (20W-40) or SAE 20W-40 type SG
motor oil (Non-Friction modified)
At 15 °C (60 °F) or lower É
Yamalube 4 (10W-30) or SAE 10W-30 type SG
motor oil (Non-Friction modified) and/or
Yamalube 4-R (15W-50) (Non-Friction modi-
fied)
(Except for USA and CDN)
API “SG” or higher grade
-20
-4-10
140
3010
5020
6830
8640 50
104
122˚CTemp.
˚F
10W-30
10W-40
20W-40
20W-50
15W-40
GENERAL SPECIFICATIONS
Page 101 of 786

SPEC
2 - 12
NOTE:
- marked portion shall be checked for torque tightening after break-in or before each race.
NOTE:
*1: Tighten the cylinder head bolts to 30 Nm (3.0 m kg, 22 ft lb) in the proper tightening sequence,
remove and retighten the cylinder head bolts to 20 Nm (2.0 m kg, 14 ft lb) in the proper tightening
sequence, and then tighten the cylinder head bolts further to reach the specified angle 180° in the
proper tightening sequence.Oil check bolt M6 × 1.0 1 10 1.0 7.2
Oil hose clamp—220.21.4
Clutch cover M6 × 1.0 7 10 1.0 7.2
Crankcase cover (right) M6 × 1.0 10 10 1.0 7.2
Crankcase cover (left) M6 × 1.0 9 10 1.0 7.2
Idle gear cover (starter motor) M6 × 1.0 2 10 1.0 7.2
Crankcase M6 × 1.0 12 12 1.2 8.7
Clutch cable holder M6 × 1.0 1 10 1.0 7.2
Oil drain bolt (crankcase rear) M10 × 1.25 1 20 2.0 14
(crankcase left) M6 × 1.0 1 10 1.0 7.2
Oil drain bolt (frame) M8 × 1.25 1 23 2.3 17
Oil strainer (frame) M14 × 1.5 1 70 7.0 50
Crankcase bearing stopper M6 × 1.0 15 10 1.0 7.2
Drive axle oil seal stopper M6 × 1.0 2 10 1.0 7.2
Ratchet wheel guide M6 × 1.0 2 12 1.2 8.7
Kickstarter M8 × 1.25 1 33 3.3 24
Screw (kickstarter) M6 × 1.0 1 7 0.7 5.1
Starter clutch M6 × 1.0 6 16 1.6 11
Primary drive gear M20 × 1.0 1 110 11.0 80
Clutch boss M20 × 1.0 1 75 7.5 54
Push lever M6 × 1.0 1 10 1.0 7.2
Clutch spring M6 × 1.0 6 8 0.8 5.8
Balancer driven gear M14 × 1.0 1 50 5.0 36
Balancer weight plate M6 × 1.0 3 10 1.0 7.2
Drive sprocket M20 × 1.0 1 75 7.5 54
Drive sprocket cover M6 × 1.0 2 8 0.8 5.8
Shift pedal M6 × 1.0 1 12 1.2 8.7
Shift guide M6 × 1.0 2 10 1.0 7.2
Stopper lever M6 × 1.0 1 10 1.0 7.2
Segment M8 × 1.25 1 30 3.0 22 Part to be tightened Thread size Q’tyTightening torque
Nm m·kg ft·lb
MAINTENANCE SPECIFICATIONS
Page 109 of 786

SPEC
2 - 20
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
SPECIFICATION
Nm mkg ftlb
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
Page 290 of 786
3 - 47
INSP
ADJ
LUBRICATION
LUBRICATION
To ensure smooth operation of all compo-
nents, lubricate your machine during setup,
after break-in, and after every race.
1All control cable
2Clutch lever pivot
3Shift pedal pivot
4Footrest pivot
5Throttle-to-handlebar contact
6Drive chain
7Tube guide cable winding portion
8Throttle cable end
9Clutch cable end
0Hot starter cable endÈUse Yamaha cable lube or equivalent on these
areas.
ÉUse SAE 10W-30 motor oil or suitable chain
lubricants.
ÊLubricate the following areas with high quality,
lightweight lithium-soap base grease.
CAUTION:
Wipe off any excess grease, and avoid get-
ting grease on the brake discs.
AAA
AA
B
CC
Page 342 of 786
4 - 13
ENGCARBURETOR
Measurement and adjustment steps:
Hold the carburetor in an upside down
position.
NOTE:
Slowly tilt the carburetor in the opposite
direction, then take the measurement
when the needle valve aligns with the float
arm.
If the carburetor is level, the weight of the
float will push in the needle valve, resulting
in an incorrect measurement.
Measure the distance between the mating
surface of the float chamber and top of the
float using a vernier calipers.
NOTE:
The float arm should be resting on the nee-
dle valve, but not compressing the needle
valve.
If the float height is not within specification,
inspect the valve seat and needle valve.
If either is worn, replace them both.
If both are fine, adjust the float height by
bending the float tab b on the float.
Recheck the float height.
EC464600
Float
1. Inspect:
Float 1
Damage → Replace.
Starter plunger
1. Inspect:
Cold starter plunger 1
Hot starter plunger 2
Wear/damage → Replace.