2010 YAMAHA YZ450F Owners Manual

5-36
SWINGARM
10. Tighten:
• Nut (connecting rod) "1"
11. Tighten:
• Nut (relay arm) "1"
12. Install:
• Bolt (lower chain tensioner) "1"
• Washer "2"
•Collar "3"
• Lower chain tensioner "4"
• Nut (lower chain tensioner) "5"13. Install:
• Drive chain support "1"
• Drive chain support cover "2"
• Bolt {drive chain support [L = 50
mm (1.97 in)]} "3"
• Nut (drive chain support) "4"
• Bolt {drive chain support cover [L
= 10 mm (0.39 in)]} "5" Nut (connecting rod):
80 Nm (8.0 m•kg, 58
ft•lb)
Nut (relay arm):
70 Nm (7.0 m•kg, 50
ft•lb)
Nut (lower chain tension-
er):
16 Nm (1.6 m•kg, 11
ft•lb)
Nut (drive chain sup-
port):
7 Nm (0.7 m•kg, 5.1
ft•lb)
Bolt (drive chain support
cover):
7 Nm (0.7 m•kg, 5.1
ft•lb)

5-37
REAR SHOCK ABSORBER
REAR SHOCK ABSORBER
REMOVING THE REAR SHOCK ABSORBER
Order Part name Q'ty Remarks
Hold the machine by placing the suitable stand
under the engine.Refer to "HANDLING NOTE".
Seat Refer to "SEAT AND SIDE COVERS" section
in the CHAPTER 4.
Silencer Refer to "EXHAUST PIPE AND SILENCER"
section in the CHAPTER 4.
1 Bolt (rear shock absorber-relay arm) 1 Hold the swingarm.
2 Bolt (rear shock absorber-frame) 1
3 Rear shock absorber 1
4 Locknut 1 Only loosening.
5 Adjuster 1 Only loosening.
6 Lower spring guide 1
7 Upper spring guide 1
8 Spring (rear shock absorber) 1
9 Bearing 2 Refer to removal section.

5-38
REAR SHOCK ABSORBER
HANDLING NOTE
• Support the machine securely so
there is no danger of it falling
over.
• This rear shock absorber is pro-
vided with a separate type tank
filled with high-pressure nitro-
gen gas. To prevent the danger
of explosion, read and under-
stand the following information
before handling the shock ab-
sorber. The manufacturer can
not be held responsible for prop-
erty damage or personal injury
that may result from improper
handling.
• Never tamper or attempt to dis-
assemble the cylinder or the
tank.
• Never throw the rear shock ab-
sorber into an open flame or
other high heat. The rear shock
absorber may explode as a re-
sult of nitrogen gas expansion
and/ or damage to the hose.
• Be careful not to damage any
part of the gas tank. A damaged
gas tank will impair the damp-
ing performance or cause a
malfunction.
• Take care not to scratch the
contact surface of the piston
rod with the cylinder; or oil
could leak out.
• Never attempt to remove the
plug at the bottom of the nitro-
gen gas tank. It is very danger-
ous to remove the plug.
• When scrapping the rear shock
absorber, follow the instruc-
tions on disposal.
NOTES ON DISPOSAL (YAMAHA
DEALERS ONLY)
Before disposing the rear shock ab-
sorber, be sure to extract the nitrogen
gas from valve "1". Wear eye protec-
tion to prevent eye damage from es-
caping gas and/or metal chips.
To dispose of a damaged or worn-
out rear shock absorber, take the
unit to your Yamaha dealer for this
disposal procedure.
REMOVING THE BEARING
1. Remove:
• Stopper ring (upper bearing) "1"
Press in the bearing while pressing its
outer race and remove the stopper
ring.
2. Remove:
• Upper bearing "1"
Remove the bearing by pressing its
outer race.
3. Remove:
• Lower bearing "1"
Remove the bearing by pressing its
outer race.
CHECKING THE REAR SHOCK
ABSORBER
1. Inspect:
• Damper rod "1"
Bends/damage→Replace rear
shock absorber assembly.
• Shock absorber "2"
Oil leaks→Replace rear shock
absorber assembly.
Gas leaks→Replace rear shock
absorber assembly.
• Spring "3"
Damage→Replace spring.
Fatigue→Replace spring.
Move spring up and down.
• Spring guide "4"
Wear/damage→Replace spring
guide.
• Bearing "5"
Free play exists/unsmooth revolu-
tion/rust →Replace.
INSTALLING THE BEARING
1. Install:
• Upper bearing "1"
Install the bearing parallel until the
stopper ring groove appears by
pressing its outer race.
Do not apply the grease on the
bearing outer race because it will
wear the rear shock absorber sur-
face on which the bearing is press
fitted.

5-39
REAR SHOCK ABSORBER
2. Install:
• Stopper ring (upper bearing) "1"
After installing the stopper ring, push
back the bearing until it contacts the
stopper ring.
3. Install:
• Lower bearing "1"
Install the bearing by pressing it on
the side having the manufacture's
marks or numbers.
INSTALLING THE SPRING (REAR
SHOCK ABSORBER)
1. Install:
• Spring "1"
• Upper spring guide "2"
• Lower spring guide "3"
2. Tighten:
•Adjuster "1"3. Adjust:
• Spring length (installed)
Refer to "ADJUSTING THE
REAR SHOCK ABSORBER
SPRING PRELOAD" section in
the CHAPTER 3.
4. Tighten:
• Locknut "1"
INSTALLING THE REAR SHOCK
ABSORBER
1. Install:
• Dust seal "1"
• O-ring "2"
• Collar "3"
• Apply the molybdenum disulfide
grease on the dust seal lips and col-
lars.
• Apply the lithium soap base grease
on the O-rings.
2. Install:
• Bushing "1"
• Collar "2"
• Dust seal "3"
• Apply the molybdenum disulfide
grease on the bearing and dust seal
lips.
• Install the dust seals with their lips
facing inward.
3. Install:
• Rear shock absorber4. Install:
• Bolt (rear shock absorber-frame)
"1"
• Washer "2"
• Nut (rear shock absorber-frame)
"3"
Apply the molybdenum disulfide
grease on the bolt.
5. Install:
• Bolt (rear shock absorber-relay
arm) "1"
• Nut (rear shock absorber-relay
arm) "2"
Apply the molybdenum disulfide
grease on the bolt.
Installed depth of the
bearing "a":
4 mm (0.16 in)
Nut (rear shock absorb-
er-frame):
56 Nm (5.6 m•kg, 40
ft•lb)
Nut (rear shock absorb-
er-relay arm):
53 Nm (5.3 m•kg, 38
ft•lb)

6-1
FUEL TANK
FUEL SYSTEM
This section is intended for those who have basic knowledge and skill concerning the servicing of Yamaha motorcycles
(e.g., Yamaha dealers, service engineers, etc.) Those who have little knowledge and skill concerning servicing are request-
ed not to undertake inspection, adjustment, disassembly, or reassembly only by reference to this manual. It may lead to
servicing trouble and mechanical damage.
FUEL TANK
REMOVING THE FUEL TANK
Order Part name Q'ty Remarks
SeatRefer to "SEAT AND SIDE COVERS" section
in the chapter 4.
Air scoop (left/right) 1/1Refer to "SEAT AND SIDE COVERS" section
in the chapter 4.
1 Fuel pump coupler 1 Disconnect.
2 Fuel hose 1 Refer to removal section.
3 Fuel tank bolt 2
4 Fuel tank 1 Refer to removal section.
5 Fuel pump bracket 1
6 Fuel pump assembly 1 Refer to removal section.
7O-ring 1
6

6-2
FUEL TANK
REMOVING THE FUEL TANK
1. Extract the fuel in the fuel tank through the fuel tank cap with a
pump.
Be careful not to damage the fuel
pump.
2. Remove: • Fuel pump coupler
Although the fuel has been re-
moved from the fuel tank be care-
ful when removing the fuel hoses,
since there may be fuel remaining
in it.
• Before disconnecting the fuel hose, clean the area around the fuel hose
connector.
• Before removing the fuel hose, place a few rags in the area under
where it will be removed.
• To disconnect the fuel hose from the fuel tank, remove the fuel hose
connector holder "a", and then slide
the fuel hose connector cover.
• Slide the fuel hose connector cover "1" in the direction of the arrow
mark, and press the buttons"2" on
both sides of the connector to re-
move the fuel hose.
• Disconnecting the hose is done by hand. There is no need to use tools.
• To prevent sand, dust, and other
foreign material from entering the
fuel pump, install the included fuel
hose joint cover 1 "3" and fuel hose
joint cover 2 "4" onto the fuel pump
and disconnected fuel hose.
3. Remove:•Fuel tank
Do not set the fuel tank down so that
the installation surface of the fuel
pump is directly under the tank.
REMOVING THE FUEL PUMP
1. Remove:•Fuel pump
Do not drop the fuel pump or give
it a strong shock.
CHECKING THE FUEL PUMP
BODY
1. Check:
• Fuel pump bodyCracks/damage → Replace fuel
pump assembly.
CHECKING THE FUEL PUMP
OPERATION
1. Check: • Fuel pump operationRefer to "CHECKING THE FUEL
PRESSURE" section.
INSTALLING THE FUEL PUMP
1. Install: •Fuel pump
• Fuel pump bracket
•Do not damage th e installation
surfaces of the fuel tank when in-
stalling the fuel pump.
• Before installing the fuel pump,
remove any dirt and other foreign
material from the installation sur-
face on the fuel tank.
• Always use a new fuel pump gas- ket.
• Install the lip on the fuel pump gas- ket upward.
• Install the fuel pump as shown in
the illustration.
• Align the projection "a" on the fuel pump with the slot in the fuel pump
bracket. Align the slot "b" on the fuel
tank damper with the projection "a"
on the fuel pump.
• Tighten the fuel pump bolts in stag- es in a crisscross pattern.
INSTALLING THE FUEL TANK
1. Install:•Fuel hose
•When installing the fuel hose,
make sure that it is securely con-
nected, and that the fuel hose
holders are in the correct posi-
tion, otherwise the fuel hose will
not be properly installed.
• Be sure not to kink or pinch the
fuel hose.
• Insert the fuel hose on the fuel pipe
until you hear a definite "click".
• Slide the fuel hose connector cover
"1" at the fuel hose end in the direc-
tion of the arrow.
• Install the fuel hose connector hold-
er "a".
• Make sure that the fuel hose and fuel pump lead are routed through
the guide on the cover.
Fuel pump bracket bolt
4 Nm (0.4 m•kg, 2.9
ft•lb)

6-3
FUEL TANK
2. Install:
• Fuel pump coupler
• Air scoop (left/right)
• Seat
Refer to "SEAT AND SIDE COV-
ERS" in the chapter 4.
CHECKING THE FUEL PRESSURE
1. Check:
• Pressure regulator operation
2. Remove the fuel tank.
Refer to "REMOVEING
THE FUEL TANK" section.
3. Connect the pressure gauge "1"
and adapter "2" to the fuel injec-
tion pipe.
4. Install the fuel tank.
Refer to "INSTALLING THE
FUEL TANK" section.
5. Start the engine.
6. Measure the fuel pressure.CHECKING AND REPLACING THE
DUMPER
1. Inspect:
• Damper 1 "1"
• Damper 2 "2"
• Damper 3 "3"
Wear/damage → Replace
• Affix dampers 1 and 3 so that the
arrow on each damper is pointing
outward.
• Affix damper 2 so that the edge of
the damper contacts the edge "a" of
the frame.
Pressure gauge
YU-03153/90890-03153
Fuel pressure adapter
YM-03186/90890-03186
Fuel pressure
312–328 kPa (3.12–3.28
kg/cm
2)
20mm
20mm
35mm 35mm

6-4
THROTTLE BODY
THROTTLE BODY
REMOVING THE THROTTLE BODY
Order Part name Q'ty Remarks
SeatRefer to "SEAT AND SIDE COVERS" section
in the chapter 4.
Air scoop (left/right)Refer to "SEAT AND SIDE COVERS" section
in the chapter 4.
Fuel tank Refer to "FUEL TANK" section.
1 Cover 1
2 Air filter case 1
3 Fuel hose 1
4 Fuel injector coupler 1 Disconnect.
5 Intake air pressure sensor coupler 1 Disconnect.(I.D. MARK "2")
6 Throttle cable cover 1
7 Throttle cable 2
8 Throttle body 1
9 Throttle body joint 1