YAMAHA YZ450F 2010 Manual Online

3-25
ELECTRICAL
TROUBLESHOOTING
The following guide for troubleshooting does not cover all the possible causes of problems. If the following problems occur,
perform the specified checks or maintenance jobs. If a problem occurs that is not listed in this manual or if the problem
cannot be corrected by the procedures provided in this manual, contact your Yamaha dealer.
Engine starting problems, engine idling speed problems, and medium and high-speed performance problems
• Engine does not start even though the kickstarter is pushed.
• Engine starts, but soon stops.
Engine idling speed problems
• Engine idling speed fluctuates.
• Engine idling speed is high.
• Engine idling speed is low.
Medium and high-speed performance problems
• Engine speed does not increase.
• Engine knocks.
• Engine speed increases suddenly.
• Loss of engine power.
INSPECTION STEPS
If the aforementioned problems have occurred, perform the following inspection steps in the order given.
Check that the fuel tank is filled with fresh gaso-
line.No good→
Fill the fuel tank.
OK↓
Check that the fuel tank breather hose is not
clogged. (Refer to "INCLUDED PARTS" section
in the CHAPTER 1.)No good→
Repair or replace.
OK↓
Adjusting the engine idling speed(Refer to "AD-
JUSTING THE ENGINE IDLLING SPEED" sec-
tion in the CHAPTER 3.)No good→
Adjust.
OK↓
Check that the fuel hose is connected properly
and is not kinked or pinched.No good→
Repair.
OK↓
Check the spark plug for dirt, the spark plug gap,
and the spark plug cap. (Refer to "CHECKING
THE SPARK PLUG" section in the CHAPTER 3.)No good→
Clean or adjust.
OK↓
Check that the air filter element is installed cor-
rectly and is not clogged. (Refer to "CLEANING
THE AIR FILTER" section in the CHAPTER 3.)No good→
Clean or repair.
OK↓
Checking the sensors, injector and ignition coil
connection.No good→
Repair or replace.
OK↓
Installed condition of ECU (Refer to "CHECKING
THE ECU" section in the CHAPTER 7.)No good→
Repair.
OK↓
Check the assembled condition of the throttle
body, and check the throttle valve and its sur-
rounding parts for dirt.No good→
Repair or clean.
OK↓
Consult a Yamaha dealer.

4-1
SEAT AND SIDE COVERS
ENGINE
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.
SEAT AND SIDE COVERS
REMOVING THE SEAT AND SIDE COVERS
Order Part name Q'ty Remarks1Seat 1
2 Air scoop (left) 1
3 Air scoop (right) 1
4 Side cover (left) 1
5 Side cover (right) 1
6 Number plate 1 Refer to removal section.
7 Rear fender 1

4-2
SEAT AND SIDE COVERS
REMOVING THE NUMBER PLATE
1. Remove:
• Bolt (number plate)
• Number plate "1"
• The projection "a" is inserted into
the band of the number plate. Pull
the band off the projection before
removal.
• Remove the clutch cable "2" from
the cable guide "b" on the number
plate.
• The projection "c" on the lower
bracket is inserted into the number
plate. Remove the number plate by
pulling it off the projection.
CHECKING AND REPLACING THE
PROTECTOR
1. Inspect:
•Protector
Wear/damage → Replace.
Affix the protector as shown.
CHECKING AND REPLACING THE
INSULATOR
1. Inspect:
• Insulator
Damage/peeled off → Re-
place.
• Before affixing the insulators to the
side cover, wipe stains etc. off its
surface with a degreasing agent or
the like.
• Make sure that the insulators do not
protrude past the edges of the side
covers.
• Affix the insulators in the following
order with the portion "a" overlap-
ping one on another.
• Insulator 1 "1"
• Insulator 2 "2"
• Insulator 3 "3"
• Insulator 4 "4"
• Insulator 5 "5"
• Insulator 6 "6"
• Insulator 7 "7"
• Insulator 8 "8"
• Insulator 9 "9"
4

4-3
EXHAUST PIPE AND SILENCER
EXHAUST PIPE AND SILENCER
REMOVING THE EXHAUST PIPE AND SILENCER
Order Part name Q'ty Remarks
Seat Refer to "SEAT AND SIDE COVERS" sec-
tion.
Side cover (left and right)Refer to "SEAT AND SIDE COVERS" sec-
tion.
Rear fenderRefer to "SEAT AND SIDE COVERS" sec-
tion.
1 Bolt (silencer clamp) 1 Only loosening.
2 Silencer clamp 1
3 Bolt (silencer) 2
4 Silencer 1
5 Bolt (exhaust pipe) 1 Only loosening.
6 Silencer clamp 1
7 Bolt (exhaust pipe 2) 1
8 Exhaust pipe 2 1
9 Nut (exhaust pipe) 3
10 Exhaust pipe 1 1
11 Gasket 3

4-4
EXHAUST PIPE AND SILENCER
12 Heat protector 1 Order Part name Q'ty Remarks

4-5
EXHAUST PIPE AND SILENCER
CHECKING THE SILENCER AND
EXHAUST PIPE
1. Inspect:
• Gasket "1"
Damage→Replace.
CHANGING THE SILENCER FIBER
For USA and CDN
2. Remove:
•Bolt "1"
• Inner pipe "2"
Do not hit the silencer stay "a" as it
may do damage to the silencer.
Remove the inner pipe while holding
the silencer in place with a vise etc.
3. Replace:
• Fiber "1" 4. Install:
• Inner pipe "1"
• Bolt "2"
• Apply heat-resistant sealant to the
areas "a" shown, making sure that
there are no gaps in the beads of
sealant.
• Take care not to allow the fiber out
of place when installing the inner
pipe.
• Apply locking agent (LOCTITE®) to
the threads of the bolts.
Except for USA and CDN
1. Remove:
• Rivet (front) "1"
• Inner pipe "2"
•Take care not to damage the rivet
fitting holes (ø4.9 mm) "a" in re-
moval.
•Do not hit the silencer stay "b" as
it may do damage to the silencer.
Remove the inner pipe while holding
the silencer in place with a vise etc.
2. Replace:
• Fiber "1"
3. Install:
• Inner pipe "1"
• Rivet (front) "2"
• Band "3"
• Apply heat-resistant sealant to the
areas "a" shown, making sure that
there are no gaps in the beads of
sealant.
• Take care not to allow the fiber out
of place when installing the inner
pipe.
• Install the band "3" with the mating
ends "b" positioned as shown.
Bolt (silencer):
8 Nm (0.8 m•kg, 5.8
ft•lb)

4-6
EXHAUST PIPE AND SILENCER
INSTALLING THE SILENCER AND
EXHAUST PIPE
1. Install:
• Gasket
• Exhaust pipe "1"
• Nut (exhaust pipe) "2"
First temporarily tighten both nuts to 7
Nm (0.7 m•kg, 5.1 ft•lb). Then retight-
en the same nut to 10 Nm (1.0 m•kg,
7.2 ft•lb).
2. Install:
• Silencer clamp (front)
• Eexhaust pipe 2 "1"
• Bolt (exhaust pipe 2) "2"
Install and temporarily tighten the ex-
haust pipe 2 with its end positioned
as shown with respect to the exhaust
pipe 1.
3. Install:
• Silencer clamp (rear)
• Silencer "1"
• Bolt (silencer) "2"
Install and temporarily tighten the si-
lencer so that its joint is positioned as
shown with respect to the exhaust
pipe 2.
4. Install:
• Bolt (exhaust pipe 2):
• Silencer clamp (front):
• Silencer clamp (rear):
Tighten while checking that their front
and rear joints are inserted in posi-
tion.
Nut (exhaust pipe):
10 Nm (1.0 m•kg, 7.2
ft•lb)
3 - 7 mm (0.12 - 0.28 in)
Bolt (silencer):
30 Nm (3.0 m•kg, 22
ft•lb)
Bolt (exhaust pipe 2):
20 Nm (2.0 m•kg, 14
ft•lb)
Silencer clamp (front):
12 Nm (1.2 m•kg, 8.7
ft•lb)
Silencer clamp (rear):
16 Nm (1.6 m•kg, 11
ft•lb)
1 - 9 mm (0.04 - 0.35 in)

4-7
RADIATOR
RADIATOR
REMOVING THE RADIATOR
Order Part name Q'ty Remarks
Drain the coolant.Refer to "CHANGING THE COOLANT" sec-
tion in the CHAPTER 3.
SeatRefer to "SEAT AND SIDE COVERS" sec-
tion.
Fuel tank Refer to "FUEL TANK" section in the CHAP-
TER 6.
Air filter caseRefer to "THROTTLE BODY" section in the
CHAPTER 6.
1 Radiator guard 2
2 Radiator hose clamp 8 Only loosening.
3 Right radiator 1
4 Radiator hose 2 1
5 Radiator hose 4 1
6 Radiator hose 3 1
7 Pipe 2/O-ring 1/1
8 Radiator breather hose 1
9 Left radiator 1
10 Radiator hose 1 1

4-8
RADIATOR
11 Pipe 1/O-ring 1/1 Order Part name Q'ty Remarks

4-9
RADIATOR
HANDLING NOTE
Do not remove the radiator cap
when the engine and radiator are
hot. Scalding hot fluid and steam
may be blown out under pressure,
which could cause serious injury.
When the engine has cooled, open
the radiator cap by the following
procedure:
Place a thick rag, like a towel, over
the radiator cap, slowly rotate the
cap counterclockwise to the de-
tent. This procedure allows any re-
sidual pressure to escape. When
the hissing sound has stopped,
press down on the cap while turn-
ing counterclockwise and remove
it.
CHECKING THE RADIATOR
1. Inspect:
• Radiator core "1"
Obstruction→Blow out with com-
pressed air through rear of the ra-
diator.
Bent fin→Repair/replace.
INSTALLING THE RADIATOR
1. Install:
• O-ring "1"
• Pipe 1 "2"
• Radiator hose 1 "3"
• O-ring "4"
• Pipe 2 "5"
• Radiator hose 3 "6"• Radiator hose 4 "7"
2. Install:
• Grommet "1"
Face the smaller portion "a" of the
grommet inward.
3. Install:
• Radiator hose 2 "1"
• Left radiator "2"
4. Install:
• Radiator breather hose "1"
• Right radiator "2"
Refer to "CABLE ROUTING DIA-
GRAM" section in the CHAPTER
2.5. Install:
• Radiator guard "1"
First fit the inner hook portion "a" and
then the outer one "b" onto the radia-
tor.
6. Install:
• Bolt (radiator guard) "1"
Pipe 1:
10 Nm (1.0 m•kg, 7.2
ft•lb)
Radiator hose 1:
2 Nm (0.2 m•kg, 1.4
ft•lb)
Pipe 2:
10 Nm (1.0 m•kg, 7.2
ft•lb)
Radiator hose 3:
2 Nm (0.2 m•kg, 1.4
ft•lb)
Radiator hose 4:
2 Nm (0.2 m•kg, 1.4
ft•lb)
Radiator hose 2:
2 Nm (0.2 m•kg, 1.4
ft•lb)
Left radiator:
10 Nm (1.0 m•kg, 7.2
ft•lb)
Right radiator:
10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (radiator guard) "1":
10 Nm (1.0 m•kg, 7.2
ft•lb)