2010 YAMAHA YZ450F engine

2-11
TIGHTENING TORQUES
TIGHTENING TORQUES
ENGINE
△- marked portion shall be checked for torque tightening after break-in or before each race.
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 8 10 1.0 7.2
Cylinder head blind plug screw M12 × 1.0 2 28 2.8 20
Oil passage plug M8 × 1.25 1 15 1.5 11
Cylinder head (stud bolt) M6 × 1.0 3 7 0.7 5.1
Cylinder head (bolt) M10 × 1.25 4 Refer to TIP.
*1
Cylinder head (bolt) M6 × 1.0 2 10 1.0 7.2
Cylinder head cover M6 × 1.0 3 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
Timing chain tensioner cap bolt M6 × 1.0 1 7 0.7 5.1
Timing chain guide stopper plate (exhaust side) M6 × 1.0 2 10 1.0 7.2
Exhaust pipe (nut) M6 × 1.0 3 10 1.0 7.2
Exhaust pipe and frame M8 × 1.25 1 20 2.0 14
△Silencer M8 × 1.25 2 30 3.0 22
Silencer clamp (front) M8 × 1.25 1 12 1.2 8.7
Silencer clamp (rear) M8 × 1.25 1 16 1.6 11
Starter knob/Idle screw M12 × 1.0 1 2 0.2 1.4
Throttle body joint M6 × 1.0 2 10 1.0 7.2
Throttle body joint clamp M5 × 0.8 1 3 0.3 2.2
△Air filter case M6 × 1.0 3 7 0.7 5.1
Air filter case cover M5 × 0.8 2 5 0.5 3.6
Air filter joint clamp M4 × 0.7 1 4 0.4 2.2
Throttle cable adjust bolt and locknut M6 × 0.75 1 4 0.4 2.9
Throttle cable (pull) M10 × 1.25 1 7 0.7 5.1
Throttle cable (return) M10 × 1.25 1 7 0.7 5.1
Throttle cable cover M5 × 0.8 2 4 0.4 2.9
Air duct M6 × 1.0 3 7 0.7 5.1
Radiator M6 × 1.0 4 10 1.0 7.2
Radiator hose clamp M6 × 1.0 8 2 0.2 1.4
Radiator pipe 1 M6 × 1.0 1 10 1.0 7.2
Radiator pipe 2 M6 × 1.0 1 10 1.0 7.2
Impeller M8 × 1.25 1 14 1.4 10
Water pump housing cover M6 × 1.0 4 10 1.0 7.2
Coolant drain bolt M6 × 1.0 1 10 1.0 7.2
Oil pump cover M4 × 0.7 1 2 0.2 1.4
Oil pump M6 × 1.0 2 10 1.0 7.2
Oil pump drive gear shaft M6 × 1.0 1 10 1.0 7.2
Oil filter element cover M6 × 1.0 2 10 1.0 7.2
Oil pressure check bolt M6 × 1.0 2 10 1.0 7.2

2-14
TIGHTENING TORQUES
△Driven sprocket and wheel hub M8 × 1.25 6 42 4.2 30
△Nipple (spoke) — 72 3 0.3 2.2
△Disc cover and rear brake caliper M6 × 1.0 2 10 1.0 7.2
△Protector and rear brake caliper M6 × 1.0 2 7 0.7 5.1
Drive chain puller adjust bolt and locknut M8 × 1.25 2 21 2.1 15
Engine mounting:
△Upper engine bracket and frame M8 × 1.25 4 45 4.5 32
△Front engine bracket and frame M8 × 1.25 4 34 3.4 24
△Engine and engine bracket (front) M10 × 1.25 1 53 5.3 38
△Engine and engine bracket (upper) M10 × 1.25 2 45 4.5 32
△Engine and frame (lower) M10 × 1.25 1 53 5.3 38
△Engine guard M6 × 1.0 1 10 1.0 7.2
Lower engine guard M6 × 1.0 3 10 1.0 7.2
△Pivot shaft and nut M16 × 1.5 1 85 8.5 61
△Relay arm and swingarm M14 × 1.5 1 70 7.0 50
△Relay arm and connecting rod M14 × 1.5 1 80 8.0 58
△Connecting rod and frame M14 × 1.5 1 80 8.0 58
△Rear shock absorber and frame M10 × 1.25 1 56 5.6 40
△Rear shock absorber and relay arm M10 × 1.25 1 53 5.3 38
△Rear shock absorber locknut M60 × 1.5 1 30 3.0 22
△Rear frame and frame (upper) M8 × 1.25 1 32 3.2 23
△Rear frame and frame (lower) M8 × 1.25 2 32 3.2 23
△Swingarm and brake hose holder M5 × 0.8 4 3 0.3 2.2
Upper drive chain tensioner M8 × 1.25 1 16 1.6 11
Lower drive chain tensioner M8 × 1.25 1 16 1.6 11
Drive chain support and swingarm M6 × 1.0 3 7 0.7 5.1
△Seal guard and swingarm M5 × 0.8 3 4 0.4 2.9
△Fuel tank mounting boss and frame M10 × 1.25 1 20 2.0 14
△Fuel tank (front) M6 × 1.0 2 9 0.9 6.5
Fuel tank bracket (front) M6 × 1.0 4 7 0.7 5.1
△Fuel tank (rear) M6 × 1.0 2 9 0.9 6.5
Fuel tank bracket (rear) M6 × 1.0 2 7 0.7 5.1
△Fuel pump M5 × 0.8 6 4 0.4 2.9
Fuel tank side cover M6 × 1.0 4 7 0.7 5.1
Fuel tank and seat set bracket M6 × 1.0 1 7 0.7 5.1
Fuel tank and fuel tank bracket M6 × 1.0 4 7 0.7 5.1
Seat M8 × 1.25 2 22 2.2 16
△Side cover M6 × 1.0 4 7 0.7 5.1
Heat protector M5 × 0.8 2 4 0.4 2.9
△Air scoop and fuel tank M6 × 1.0 2 9 0.9 6.5
△Air scoop and air duct M6 × 1.0 2 7 0.7 5.1
radiator and radiator guard M6 × 1.0 2 10 1.0 7.2
△Air scoop and radiator guard M6 × 1.0 2 7 0.7 5.1
△Front fender M6 × 1.0 4 10 1.0 7.2Part to be tightened Thread size Q'tyTightening torque
Nm m•kg ft•lb

2-16
TIGHTENING TORQUES
GENERAL TORQUE
SPECIFICATIONS
This chart specifies torque for stan-
dard fasteners with standard I.S.O.
pitch threads. Torque specifications
for special components or assem-
blies are included in the applicable
sections of this book. To avoid war-
page, tighten multi-fastener assem-
blies in a crisscross fashion, in
progressive stages, until full torque is
reached. Unless otherwise specified,
torque specifications call for clean,
dry threads. Components should be
at room temperature.A. Distance between flats
B. Outside thread diameter
DEFINITION OF UNITS
A
(Nut)B
(Bolt
)TORQUE SPECIFI-
CATION
Nm m•kg ft•lb
10
mm6 mm 6 0.6 4.3
12
mm8 mm 15 1.5 11
14
mm10
mm30 3.0 22
17
mm12
mm55 5.5 40
19
mm14
mm85 8.5 61
22
mm16
mm130 13 94
Unit Read Definition Measure
mm
millimeter 10-3 meter Length
cmcentimeter 10-2 meter Length
kgkilogram 103 gram Weight
NNewton 1 kg × m/sec2Force
NmNewton meter N × m Torque
m•kgMeter kilogram m × kg Torque
PaPascal N/m2Pressure
N/mmNewton per millimeter N/mm Spring rate
LLiter — Volume or capacity
cm3Cubic centimeter — Volume or capacity
r/minRevolution per minute — Engine speed

2-21
CABLE ROUTING DIAGRAM
1. Clutch cable
2. Throttle cable (return)
3. Throttle cable (pull)
4. Cable holder
5. Clamp
6. Rectifier/regulator
7. Ignition coil
8. Ignition coil coupler
9. AC magneto coupler
10. Radiator hose 2
11. Ground lead terminal
12. Plug cap
13. Ignition coil bracket
14. Clamp (lock)
15. Clamp (clip)
16. AC magneto lead
17. ECU bracketA. Pass the clutch cable, throttle
cables, and engine stop switch
lead through the cable holder.
Pass the clutch cable through
the lower guide only.
B. Route the engine stop switch
lead to the inside of the clip.
C. Fasten the rectifier/regulator
lead and engine stop switch lead
(wire harness end).
D. Insert the projection on the en-
gine stop switch coupler into the
hole in the bracket.
E. Insert the projection on the recti-
fier/regulator coupler into the
hole in the bracket.
F. Position the ignition coil bracket
to the outside of the ignition coil,
and insert the bolts from the igni-
tion coil side.
G. Fasten the AC magneto lead to
the ignition coil bracket with a
plastic locking tie, making sure
to position the tie above the low-
er mounting portion of the brack-
et. Face the buckle of the plastic
locking tie forward, and then cut
off the excess end of the tie.
H. Route the ignition coil lead be-
tween the condenser and the ig-
nition coil.
I. Fit the clip portion of the clamp
into the ignition coil bracket and
fasten the clutch cable with the
locking portion of the clamp.
J. Route the clutch cable to the
outside of the AC magneto lead.
K. Route the throttle cables under
radiator hose 2, making sure not
to twist the cables.
L. Route the AC magneto lead to
the inside of the throttle cables
and clutch cable.
M. Install the ground lead terminal
between the ECU bracket and
the cable holder, making sure to
position the terminal between
the stoppers.
N. Push in the spark plug cap com-
pletely, making sure that there is
no gap between the cylinder
head cover and the cap.
O. Apply sealant to the slit and in-
ner surface of the grommet, and
then install the grommet at the
position shown.

2-23
CABLE ROUTING DIAGRAM
1. Tension pipe
2. Coolant temperature sensor
coupler
3. Front engine bracket
4. Fuel pump coupler
5. Fuel pump
6. Intake air temperature sensor
coupler
7. Radiator hose 2
8. Radiator breather hose
9. Radiator hose 1
10. Radiator hose 4
11. Radiator pipe 2
12. Radiator hose 3
13. Cylinder head breather hose
14. Frame
15. ECU (electronic control unit)
16. ECU bracket
17. Main harness
18. AC magneto lead
19. Throttle position sensor lead
20. Condenser lead
21. Coolant temperature sensor
lead
22. Ignition coil lead
23. CondenserA. Fasten the wire harness at the
positioning tape to the ECU
bracket with a plastic locking tie.
Face the buckle of the plastic
locking tie downward, and then
cut off the excess end of the tie.
B. Install the cover onto the wire
harness coupler.
C. Route the condenser lead, throt-
tle position sensor lead, coolant
temperature sensor lead, igni-
tion coil lead, and AC magneto
lead under radiator hose 2.
D. Connect the vacuum hose to the
atmospheric pressure sensor,
and then fasten the hose with
the clamp. Make sure to face the
moving part of the sensor rear-
ward.
E. After connecting the condenser
coupler, install the coupler cover
onto the coupler.
F. After connecting the throttle po-
sition sensor coupler, install the
coupler cover onto the coupler.
G. Fasten the AC magneto lead,
condenser lead, throttle position
sensor lead, coolant tempera-
ture sensor lead, and ignition
coil lead to the frame with the
plastic band, making sure to po-
sition the band between the igni-
tion coil bracket and the tension
pipe. Face the buckle of the
plastic band to the right with the
end pointing rearward.
H. Point the end of the vacuum
hose rearward.
I. Fit the bracket into the hole in
the rubber portion of the con-
denser.
J. Fasten the radiator breather
hose to the frame with the plas-
tic band, making sure to position
the band above the front engine
bracket. Face the buckle of the
plastic band outward with the
end pointing rearward.
K. After connecting the coolant
temperature sensor coupler, in-
stall the coupler cover onto the
coupler.L. Route the radiator breather hose
between the down tubes.
M. Fasten the fuel hose and fuel
pump lead with the plastic band,
making sure to position the band
between the bend in the fuel
hose protector and the end of
the protector. Point the end of
the plastic band upward.
N. Insert the projection on the joint
coupler into the hole in the
bracket, and then install the cou-
pler cover onto the coupler.
O. Route the atmospheric pressure
sensor lead, intake air pressure
sensor lead, intake air tempera-
ture sensor lead, fuel injector
lead, and fuel pump lead above
radiator hose 2. Position the
joint coupler above radiator
hose 2.
P. Route the radiator breather hose
to the inside of radiator hose 1
and the front engine bracket.
Q. Hose installation position
(1.3–3.3 mm, 0.05–0.13 in)
R. Clip installation position (0–2.0
mm, 0–0.08 in)
S. Install the washer so that it con-
tacts the bolt head.
T. Install the collar so that the
flange on the collar contacts the
ECU bracket.

2-26
CABLE ROUTING DIAGRAM
1. Throttle cable
2. Clutch cable
3. Clamp
4. Engine stop switch lead
5. Hose guide
6. Main harnessA. Route the clutch cable to the
rear of the number plate band.
B. Fasten the engine stop switch
lead to the handlebar.
C. Route the brake hose to the
front of the number plate.
D. Pass the clutch cable through
the cable guide on the number
plate.

3-1
MAINTENANCE INTERVALS
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.
• Periodic inspection is essential in making full use of the machine performance. The service life of the parts varies sub-
stantially according to the environment in which the machine runs (e.g., rain, dirt, etc.). Therefore, earlier inspection is
required by reference to the list below..
ItemAfter
break-
inEvery
race
(about
2.5
hours)
Every
third
(about
7.5
hours)Every
fifth
(about
12.5
hours)
As re-
quiredRemarks
ENGINE OIL
Replace●●
VALVES
Check the valve clearances●●The engine must be cold.
Inspect●Check the valve seats and valve
stems for wear.
Replace●
VALVE SPRINGS
Inspect●Check the free length and the tilt.
Replace●
VALVE LIFTERS
Inspect●Check for scratches and wear.
Replace●
CAMSHAFTS Inspect the camshaft surface.
Inspect●Inspect the decompression system.
Replace●
CAMSHAFT SPROCKETS
Inspect●Check for wear on the teeth and for
damage.
Replace●
PISTON
Inspect●Inspect crack.
Clean●Inspect carbon deposits and eliminate
them.
Replace●●Replace the piston, piston pin, piston
pin clip, and piston ring all as a set.
PISTON RING
Inspect●Check ring end gap.
Replace●●Replace the piston, piston pin, piston
pin clip, and piston ring all as a set.
PISTON PIN
Inspect●
Replace●●Replace the piston, piston pin, piston
pin clip, and piston ring all as a set.
3

3-3
MAINTENANCE INTERVALS
AIR FILTER
Clean and lubricate●●Use foam air-filter oil or equivalent oil.
Replace●
OIL FILTER
Replace●●
ENGINE GUARD
Replace●Breakage
FRAME
Clean and inspect●●
FUEL TANK, FUEL PUMP
inspect●●
FUEL HOSE
Inspect●
Replace●Every four years
BRAKES
Adjust lever position and pedal
height●●
Lubricate pivot point●●
Check brake disc surface●●
Check fluid level and leakage●●
Retighten brake disc bolts, cali-
per bolts, master cylinder bolts
and union bolts●●
Replace pads●
Replace brake fluid●Every one year
FRONT FORKS
Inspect and adjust●●
Replace oil●●Suspension oil "S1"
Replace oil seal●
FRONT FORK OIL SEAL AND
DUST SEAL
Clean and lube●●Lithium base grease
PROTECTOR GUIDE
Replace●
REAR SHOCK ABSORBER
Inspect and adjust●●
Lube●(After
rain
ride)●Molybdenum disulfide grease
Retighten●●
DRIVE CHAIN GUIDE AND
ROLLERS
Inspect●● ItemAfter
break-
inEvery
race
(about
2.5
hours)
Every
third
(about
7.5
hours)Every
fifth
(about
12.5
hours)
As re-
quiredRemarks