2003 YAMAHA YZ450F radiator cap

GEN
INFO

1 - 1
DESCRIPTION
EC100000
GENERAL INFORMATION
EC110000
DESCRIPTION
1
Clutch lever
2
Hot starter lever
3
Front brake lever
4
Throttle grip
5
Radiator cap
6
Fuel tank cap
7
“ENGINE STOP” button
8
Kick starter
9
Fuel tank
0
Radiator
A
Coolant drain bolt
B
Rear brake pedal
C
Valve joint
D
Fuel cock
E
Cold starter knob
F
Drive chain
G
Air cleaner
H
Shift pedal
I
Oil dipstick
J
Front fork
NOTE:


The machine you have purchased may differ
slightly from those shown in the following.

Designs and specifications are subject to
change without notice.

GEN
INFO
1 - 7
SPECIAL TOOLS
EC140001
SPECIAL TOOLS
The proper special tools are necessary for complete and accurate tune-up and assembly. Using the
correct special tool will help prevent damage caused by the use of improper tools or improvised
techniques. The shape and part number used for the special tool differ by country, so two types are
provided. Refer to the list provided to avoid errors when placing an order.
NOTE:
For U.S.A. and Canada, use part number starting with “YM-” , “YU-” or “ACC-”.
For others, use part number starting with “90890-”.
Part number Tool name/How to use Illustration
YU-1135-A, 90890-01135 Crankcase separating tool
These tool is used to remove the crankshaft from
either case.YU-1135-A 90890-01135
YU-1235, 90890-01235 Rotor holding tool
This tool is used when loosening or tightening the fly-
wheel magneto securing nut.YU-1235 90890-01235
YU-3097, 90890-01252
YU-1256Dial gauge and stand
Stand
These tools are used to check each part for runout or
bend.YU-3097
YU-125690890-01252
YU-90050, 90890-01274
YU-90050, 90890-01275
YU-91044, 90890-04081
YU-90063, 90890-01278Crankshaft installing tool
Crankshaft installing pot
Crankshaft installing bolt
Spacer (crankshaft installer)
Adapter (M12)
These tools are used to install the crankshaft.YU-90050
YU-90063
YU-9104490890-01274
90890-01275
90890-01278
90890-04081
YU-1304, 90890-01304 Piston pin puller
This tool is used to remove the piston pin.YU-1304 90890-01304
YU-24460-01, 90890-01325
YU-33984, 90890-01352Radiator cap tester
Adapter
These tools are used for checking the cooling sys-
tem.YU-24460-01
YU-3398490890-01325
90890-01352
YM-1189, 90890-01189 Flywheel puller
This tool is used to remove the flywheel magneto.YM-1189 90890-01189

SPEC

2 - 9
MAINTENANCE SPECIFICATIONS
Lubrication system:
Oil filter type Wire mesh type ----
Oil pump type Trochoid type ----
Tip clearance “A”0.12 mm or less
(0.0047 in or less)0.20 mm
(0.008 in)
Tip clearance “B”0.09 ~ 0.17 mm
(0.0035 ~ 0.0067 in)0.24 mm
(0.009 in)
Side clearance 0.03 ~ 0.10 mm
(0.0012 ~ 0.0039 in)0.17 mm
(0.007 in)
Bypass valve setting pressure 40 ~ 80 kPa (0.4 ~ 0.8 kg/cm
2

,
5.69 ~ 11.38 psi)----
Cooling:
Radiator core size
Width 117.8 mm (4.6 in) ----
Height 260 mm (10.2 in) ----
Thickness 32 mm (1.26 in) ----
Radiator cap opening pressure 110 kPa (1.1 kg/cm
2

, 15.6 psi) ----
Radiator capacity (total) 0.71 L (0.62 Imp qt, 0.75 US qt) ----
Water pump
Type Single-suction centrifugal pump ----Item Standard Limit

SPEC

2 - 11
MAINTENANCE SPECIFICATIONS
Part to be tightened Thread size Q’tyTightening torque
Nm m·kg ft·lb
Spark plug M10S
×
1.0 1 13 1.3 9.4
Camshaft cap M6
×
1.0 10 10 1.0 7.2
Cylinder head blind plug screw M12
×
1.0 1 37 3.7 27
Cylinder head (stud bolt) M6
×
1.0 2 7 0.7 5.1
M8
×
1.25 1 15 1.5 11
(bolt) M10
×
1.25 4 Refer to NOTE.*
1

(nut) M6
×
1.0 2 10 1.0 7.2
Cylinder head cover M6
×
1.0 2 10 1.0 7.2
Cylinder M6
×
1.0 1 10 1.0 7.2
Timing chain tensioner M6
×
1.0 2 10 1.0 7.2
Tensioner cap bolt M6
×
1.0 1 7 0.7 5.1
Timing chain guide (rear) M6
×
1.0 2 10 1.0 7.2
Exhaust pipe (nut) M8
×
1.25 1 13 1.3 9.4
(bolt) M8
×
1.25 1 24 2.4 17
Silencer M8
×
1.25 2 35 3.5 25
Silencer clamp M8
×
1.25 1 20 2.0 14
Exhaust pipe protector M6
×
1.0 3 10 1.0 7.2
Clamp (cylinder head side) M5
×
0.8 1 3 0.3 2.2
Clamp (carburetor side) M4
×
0.7 1 3 0.3 2.2
Air filter case M6
×
1.0 2 8 0.8 5.8
Air filter joint clamp M6
×
1.0 1 3 0.3 2.2
Air filter joint and air filter case M5
×
0.8 1 4 0.4 2.9
Throttle cable cover M5
×
0.8 2 4 0.4 2.9
Hot starter plunger M12
×
1.0 1 2 0.2 1.4
Air filter element M6
×
1.0 1 2 0.2 1.4
Radiator panel (upper) M6
×
1.0 2 10 1.0 7.2
Radiator M6
×
1.0 6 10 1.0 7.2
Radiator hose clamp M6
×
1.0 8 2 0.2 1.4
Radiator pipe 1, 2 M10
×
1.0 2 10 1.0 7.2
Impeller M8
×
1.25 1 14 1.4 10
Water pump housing cover M6
×
1.0 3 10 1.0 7.2
Coolant drain bolt M6
×
1.0 1 10 1.0 7.2
Oil pump cover M4
×
0.7 1 3 0.3 2.2
Oil pump M6
×
1.0 3 10 1.0 7.2
Engine oil drain bolt (oil filter) M6
×
1.0 1 10 1.0 7.2
Oil filter cover M6
×
1.0 2 10 1.0 7.2
Oil delivery pipe 1 M10
×
1.25 1 20 2.0 14
M8
×
1.25 2 18 1.8 13
Oil delivery pipe 2 M6
×
1.0 1 10 1.0 7.2
Oil hose M6
×
1.0 2 10 1.0 7.2
Oil check bolt M6
×
1.0 1 10 1.0 7.2
Oil hose clamp–2 2 0.2 1.4
Clutch cover M6 × 1.0 7 10 1.0 7.2

3 - 2
INSP
ADJ

MAINTENANCE INTERVALS
SHIFT FORK, SHIFT CAM, GUIDE BAR
Inspect
●
Inspect wear
ROTOR NUT
Retighten
●

●

MUFFLER
Inspect and retighten
Clean
Replace
●

●

●

●
* Whichever comes first
CRANK
Inspect and clean
●

●

CARBURETOR
Inspect, adjust and clean
●

●
When using a high-pres-
sure washer, make sure
that water does not enter
the accelerator pump.
SPARK PLUG
Inspect and clean
Replace
●

●

●

DRIVE CHAIN
Lubricate, slack, alignment
Replace
●

●

●
Use chain lube
Chain slack: 40 ~ 50 mm
(1.6 ~ 2.0 in)
COOLING SYSTEM
Check coolant level and leakage
Check radiator cap operation
Replace coolant
Inspect hoses
●

●

●

●

●
Every two years
OUTSIDE NUTS AND BOLTS
Retighten
●

●
Refer to “STARTING
AND BREAK-IN” section
in the CHAPTER 1.
AIR FILTER
Clean and lubricate
Replace
●

●

●
Use foam air-filter oil or
equivalent oil
OIL FILTER
Replace
●

●

OIL STRAINER (frame)
Clean
●

FRAME
Clean and inspect
●

●

FUEL TANK, COCK
Clean and inspect
●

●

BRAKES
Adjust lever position and pedal height
Lubricate pivot point
Check brake disc surface
Check fluid level and leakage
Retighten brake disc bolts, caliper
bolts, master cylinder bolts and union
bolts
Replace pads
Replace brake fluid
●

●

●

●

●

●

●

●

●

●

●

●
Every one year
FRONT FORKS
Inspect and adjust
Replace oil
Replace oil seal
●

●

●

●

●
Suspension oil “01” ItemAfter
break-inEvery
race
Every
third
(or
500 km)Every
fifth
(or
1,000 km)
As re-
quiredRemarks


3

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 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.1-17
Engine oilCheck that the oil level is correct. Check the crankcase and
frame oil line for leakage.P.3-13 ~ 17
Gear shifter and clutchCheck that gears can be shifted correctly in order and that the
clutch operates smoothly.P.3-9
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
Brakes Check the play of front brake and effect of front and rear brake. P.3-24 ~ 30
ChainCheck chain slack and alignment. Check that the chain is lubri-
cated properly.P.3-31 ~ 33
WheelsCheck for excessive wear and tire pressure. Check for loose
spokes and have no excessive play.P.3-41 ~ 42
SteeringCheck that the handlebar can be turned smoothly and have no
excessive play.P.3-42 ~ 43
Front forks and rear shock
absorberCheck that they operate smoothly and there is no oil leakage. P.3-33 ~ 40
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.3-31
Lubrication Check for smooth operation. Lubricate if necessary. P.3-44
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P.1-22
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 ~ 21

3 - 5
INSP
ADJ
EC350000
ENGINE
EC351011
COOLANT LEVEL INSPECTION
WARNING
Do not remove the radiator cap 1, drain
bolt and hoses when the engine and radia-
tor are hot. Scalding hot fluid and steam
may be blown out under pressure, which
could cause serious injury.
When the engine has cooled, place a thick
towel over the radiator cap, slowly rotate
the cap counterclockwise to the detent.
This procedure allows any residual pres-
sure to escape. When the hissing sound
has stopped, press down on the cap while
turning counterclockwise and remove it.
CAUTION:
Hard water or salt water is harmful to the
engine parts. You may use distilled water, if
you can’t get soft water.
1. Place the machine on a level place, and
hold it in an upright position.
2. Remove:
Radiator cap
3. Check:
Coolant level a
Coolant level low → Add coolant.
1Radiator
ENGINE/COOLANT LEVEL INSPECTION

3 - 6
INSP
ADJ
COOLANT REPLACEMENT
EC353011
COOLANT REPLACEMENT
WARNING
Do not remove the radiator cap when the
engine is hot.
CAUTION:
Take care so that coolant does not splash
on painted surfaces. If it splashes, wash it
away with water.
1. Place a container under the engine.
2. Remove:
Engine guard 1
Coolant drain bolt 2
3. Remove:
Radiator cap
Drain the coolant completely.
4. Clean:
Cooling system
Thoroughly flush the cooling system
with clean tap water.
5. Install:
Copper washer
Coolant drain bolt
Engine guard
Bolt (engine guard)
6. Fill:
Radiator
Engine
To specified level.
Recommended coolant:
High quality ethylene glycol
anti-freeze containing anti-
corrosion for aluminum engine
Coolant 1 and water (soft water) 2
mixing ratio:
50 %/50 %
Coolant capacity:
1.2 L (1.06 Imp qt, 1.27 US qt)
New
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
T R..34 Nm (3.4 m · kg, 24 ft · lb)