2003 YAMAHA WR 450F carburetor

2 - 23
SPEC

CABLE ROUTING DIAGRAM
EC240000
CABLE ROUTING DIAGRAM
1
Fuel tank breather hose
2
Clamp
3
Diode
4
Wire harness
5
Hot starter cable
6
Negative battery lead
7
Starter motor lead
8
TPS (throttle position sen-
sor) lead
9
Neutral switch lead
0
Oil hose
A
Hose holder
B
Radiator hose 4
C
Cylinder head breather hose
D
AC magneto lead
E
Radiator hose 1
F
Oil tank breather hose
G
Lights switch lead
H
Brake hose
I
Hose guide
J
Carburetor breather hose
K
Overflow hose
LCoolant reservoir tank breather
hose
ÅInsert the fuel tank breather
hose into the hole in the steering
shaft cap.
ıFasten the diode of the wire har-
ness and rectifier/regulator lead
(at its protecting tube) to the
frame at the white tape for the
diode with a plastic locking tie
and cut off the tie end.ÇFasten the wire harness, recti-
fier/regulator lead, coolant res-
ervoir hose and hot starter cable
to the frame with a plastic lock-
ing tie and cut off the tie end.
ÎFasten the wire harness, recti-
fier/regulator lead and coolant
reservoir hose to the frame with
a plastic locking tie and cut off
the tie end.
‰Fasten the wire harness to the
frame at its white tape with a
plastic locking tie and cut off the
tie end.

2 - 24
SPECCABLE ROUTING DIAGRAM
ÏFasten the wire harness, TPS
lead (in the wire harness),
starter motor lead and negative
battery lead to the frame with a
plastic locking tie and cut off
the tie end.
ÌMake sure that the TPS cou-
pler does not go out the chas-
sis.
ÓFasten the TPS lead to the
frame with a plastic band.
ÈFasten the neutral switch lead
and oil hose together with the
plastic locking ties and cut off
the tie ends.
ÔPass the cylinder head
breather hose through the hose
holder.Fasten the neutral switch lead
to the frame with a plastic band
ends outward.
ÒFasten the neutral switch lead
and AC magneto lead to the
frame with a plastic band.
˜Pass the cylinder head
breather hose on the outside of
the radiator hose 1 and on the
inside of the radiator pipe (radi-
ator hose 4).
ˆPass the oil tank breather hose
on the outside of the AC mag-
neto lead, neutral switch lead,
lights switch lead, wire harness
and cylinder head breather
hose.ØPass the wire harness on the
outside of the neutral switch
lead and AC magneto lead.
∏Fit the brake hose into the
guides on the protector.
ŒPass the wire harness through
the cable guide.
ÂFasten the AC magneto lead,
neutral switch lead and lights
switch lead to the cable guide
at their protecting tube with a
plastic locking tie and cut off
the tie end.
ÍPass the carburetor breather
hoses, overflow hose and cool-
ant reservoir tank breather
hose so that the hoses do not
contact the rear shock
absorber.

2 - 25
SPECCABLE ROUTING DIAGRAM
1Hot starter cable
2Clutch cable
3Throttle cable (return)
4Throttle cable (pull)
5Ignition coil
6Negative battery lead
7Starter motor lead
8Coolant reservoir tank
breather hose
9Rectifier/regulator
0Cable holder
ACoolant reservoir hose
BRectifier/regulator lead
CClamp
DCDI unit lead
ECDI unit
FCDI unit band
GCDI unit stay (frame)
HCable bracketIRectifier/regulator bracket
ÅPass the throttle cables, clutch
cable and hot starter cable through
the cable guides.
ıPass the throttle cables, clutch
cable and hot starter cable between
the radiator and frame, then over
the middle radiator mounting boss.
ÇPass the throttle cables and clutch
cable on the outside of the ignition
coil.
ÎPass the carburetor breather hose
(throttle cable cover) through the
hose holder.
‰Fasten the coolant reservoir tank
breather hose and carburetor
breather hoses together with a
plastic locking tie.ÏFasten the grommet of the clutch
cable with the cable holder.
ÌFasten the CDI unit lead to the
frame with a plastic locking tie ends
at the lower of the frame and cut off
the tie end.
ÓInsert the CDI unit band over the
CDI unit stay (frame) as far as pos-
sible.
ÈFasten the starter motor lead and
negative battery lead to the cable
bracket in its slot with a plastic lock-
ing tie and cut off the tie end.
ÔFasten the rectifier/regulator lead to
the rectifier/regulator bracket with a
plastic locking tie and cut off the tie
end.

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
*SPARK ARRESTER
Clean
(Every
six
months)
●
CRANK
Inspect and clean
●

●

CARBURETOR
Inspect, adjust and clean
●

●

SPARK PLUG
Inspect and clean
Replace
●

●

●

DRIVE CHAIN
Lubricate, slack, alignment
Replace
●

●

●
Use chain lube
Chain slack: 40 ~ 50 mm
(1.57 ~ 1.97 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 ItemAfter
break-inEvery
race
Every
third
(or
500 km)Every
fifth
(or
1,000 km)
As re-
quiredRemarks


3

3 - 19
INSP
ADJIDLE SPEED ADJUSTMENT/
VALVE CLEARANCE ADJUSTMENT
EC35M021
IDLE SPEED ADJUSTMENT
1. Start the engine and thoroughly warm it
up.
2. Adjust:
Idle speed
Adjustment steps:
Adjust the pilot screw.
Refer to “PILOT SCREW ADJUSTMENT”
section.
Turn the throttle stop screw 1 until the
engine runs at the lowest possible speed.
To increase idle speed →
Turn the throttle stop screw 1 in a.
To decrease idle speed →
Turn the throttle stop screw 1 out b.
Engine idling speed:
1,700 ~ 1,900 r/min
VALVE CLEARANCE ADJUSTMENT
NOTE:
The valve clearance should be adjusted
when the engine is cool to the touch.
The piston must be at Top Dead Center
(T.D.C.) on compression stroke to check or
adjust the valve clearance.
1. Remove:
Seat
Fuel tank
Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section in the CHAPTER 4.
2. Remove:
Carburetor
Refer to “CARBURETOR” section in
the CHAPTER 4.
Spark plug cap
Engine stay (upper)
Cylinder head cover
Refer to “CAMSHAFTS” section in the
CHAPTER 4.
3. Remove:
Timing plug 1
Straight plug 2
O-ring
1
2

3 - 48
INSP
ADJ
ELECTRICAL/SPARK PLUG INSPECTION
EC370000
ELECTRICAL
EC371001
SPARK PLUG INSPECTION
1. Remove:
Spark plug
2. Inspect:
Electrode 1
Wear/damage → Replace.
Insulator color 2
Normal condition is a medium to light
tan color.
Distinctly different color → Check the
engine condition.
NOTE:
When the engine runs for many hours at low
speeds, the spark plug insulator will become
sooty, even if the engine and carburetor are in
good operating condition.
3. Measure:
Plug gap a
Use a wire gauge or thickness gauge.
Out of specification → Regap.
Spark plug gap:
0.7 ~ 0.8 mm (0.028 ~ 0.031 in)
4. Clean the plug with a spark plug cleaner
if necessary.
5. Tighten:
Spark plug
NOTE:
Before installing a spark plug, clean the gas-
ket surface and plug surface.
Finger-tighten a the spark plug before
torquing to specification b.
T R..13 Nm (1.3 m · kg, 9.4 ft · lb)

4 - 8
ENGCARBURETOR
CARBURETOR
7 4
108
9
T R..2 Nm (0.2 m •
kg, 1.4 ft • Ib)
2
3
75
5
T R..4 Nm (0.4 m •
kg, 2.9 ft • Ib)
T R..3 Nm (0.3 m • kg, 2.2 ft • Ib)
6
T R..3 Nm (0.3 m • kg, 2.2 ft • Ib)
1
T R..4 Nm (0.4 m •
kg, 2.9 ft • Ib)
T R..11 Nm (1.1 m •
kg, 8.0 ft • Ib)
Extent of removal:1 Carburetor removal
Extent of removal Order Part name Q’ty Remarks
CARBURETOR REMOVAL
Preparation for removal Fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
1 Clamp 1
2 Band 1
3 TPS coupler 1
4 Throttle cable cover 1
5 Throttle cable 2
6 Clamp (air cleaner joint) 1 Loosen the screw (air cleaner joint).
7 Clamp (carburetor joint) 2 Loosen the screws (carburetor joint).
8 Hot starter plunger 1
9 Carburetor 1
10Carburetor joint
1
1

4 - 9
ENGCARBURETOR
CARBURETOR DISASSEMBLY
Extent of removal:1 Carburetor disassembly
Extent of removal Order Part name Q’ty Remarks
CARBURETOR DISASSEMBLY
1Breather hose 4
2Valve lever housing cover 1
3Screw (throttle shaft) 1
4Throttle valve 1
5Needle holder 1
6Jet needle 1
7Cover 1
8Spring 1
9Diaphragm (accelerator pump) 1
0Air cut valve cover 1
ASpring (air cut valve) 1
BDiaphragm (air cut valve) 1
CFloat chamber 1
DLeak jet 1
EPilot screw 1 Refer to “REMOVAL POINTS”.
FFloat pin 1
GFloat 1
1