2014 YAMAHA YZ450F tire pressure

CHASSIS SPECIFICATIONS
2-8
EAS1SL1054
CHASSIS SPECIFICATIONS
Chassis
Frame type Semi double cradle
Caster angle 27.08 ° (USA) (CAN)
27.50 ° (EUR)
27.67 ° (JPN)
27.58 ° (AUS) (NZL) (ZAF)
Trail 120 mm (4.7 in) (USA) (CAN)
122 mm (4.8 in) (EUR)
124 mm (4.9 in) (JPN) (AUS) (NZL) (ZAF)
Front wheel
Wheel type Spoke wheel
Rim size 21  1.60
Rim material Aluminum
Wheel travel 310.0 mm (12.20 in)
Radial wheel runout limit 2.0 mm (0.08 in)
Lateral wheel runout limit 2.0 mm (0.08 in)
Wheel axle bending limit 0.50 mm (0.02 in)
Rear wheel
Wheel type Spoke wheel
Rim size 19  2.15
Rim material Aluminum
Wheel travel 315.0 mm (12.40 in)
Radial wheel runout limit 2.0 mm (0.08 in)
Lateral wheel runout limit 2.0 mm (0.08 in)
Wheel axle bending limit 0.50 mm (0.02 in)
Front tire
Type With tube
Size 80/100-21 51M
Manufacturer/model DUNLOP/MX51FA (USA) (CAN)
PIRELLI/MID SOFT 32 (EUR)
BRIDGESTONE/M601 (JPN)
DUNLOP/MX51FA (AUS) (NZL) (ZAF)
Rear tire
Type With tube
Size 120/80-19 63M (USA) (CAN)
110/90-19 62M (EUR) (JPN)
120/80-19 63M (AUS) (NZL) (ZAF)
Manufacturer/model DUNLOP/MX51 (USA) (CAN)
PIRELLI/MID SOFT 32 (EUR)
BRIDGESTONE/M602 (JPN)
DUNLOP/MX51 (AUS) (NZL) (ZAF)
Tire air pressure (measured on cold tires)
Front 100 kPa (1.00 kgf/cm2, 15 psi)
Rear 100 kPa (1.00 kgf/cm2, 15 psi)
Front brake
Type Single disc brake
Operation Right hand operation
Front disc brake
Disc outside diameter  thickness 250.0  3.0 mm (9.84  0.12 in)

3
PERIODIC CHECKS AND ADJUSTMENTS
MAINTENANCE INTERVALS.......................................................................... 3-1
MAINTENANCE INTERVALS .................................................................... 3-1
PRE-OPERATION INSPECTION AND MAINTENANCE................................. 3-7
GENERAL INSPECTION AND MAINTENANCE........................................ 3-7
ENGINE............................................................................................................ 3-8
CHECKING THE COOLANT LEVEL .......................................................... 3-8
CHECKING THE COOLING SYSTEM ....................................................... 3-8
CHANGING THE COOLANT...................................................................... 3-8
CHECKING THE RADIATOR CAP ............................................................ 3-9
CHECKING THE RADIATOR CAP OPENING PRESSURE ...................... 3-9
CHECKING THE COOLANT CIRCULATORY SYSTEM FOR LEAKS .... 3-10
ADJUSTING THE CLUTCH LEVER POSITION ...................................... 3-10
ADJUSTING THE CLUTCH LEVER FREE PLAY .................................... 3-10
ADJUSTING THE THROTTLE GRIP FREE PLAY .................................. 3-11
LUBRICATING THE THROTTLE CABLE ................................................ 3-12
CLEANING THE AIR FILTER ELEMENT................................................. 3-12
CHECKING THE THROTTLE BODY JOINT ............................................ 3-13
CHECKING THE BREATHER HOSES .................................................... 3-13
CHECKING THE EXHAUST SYSTEM..................................................... 3-13
CHECKING THE FUEL LINE ................................................................... 3-14
CHECKING THE ENGINE OIL LEVEL..................................................... 3-14
CHANGING THE ENGINE OIL ................................................................ 3-15
ADJUSTING THE ENGINE IDLING SPEED ............................................ 3-16
ADJUSTING THE VALVE CLEARANCE ................................................. 3-17
CHASSIS........................................................................................................ 3-21
BLEEDING THE BRAKE SYSTEM .......................................................... 3-21
CHECKING THE BRAKE HOSE .............................................................. 3-22
ADJUSTING THE FRONT BRAKE .......................................................... 3-22
ADJUSTING THE REAR BRAKE ............................................................. 3-23
CHECKING THE FRONT BRAKE PADS ................................................. 3-23
CHECKING THE REAR BRAKE PADS ................................................... 3-25
CHECKING THE REAR BRAKE PAD INSULATOR ................................ 3-26
CHECKING THE BRAKE FLUID LEVEL.................................................. 3-26
ADJUSTING THE DRIVE CHAIN SLACK ................................................ 3-27
CHECKING THE FRONT FORK LEGS ................................................... 3-28
CHECKING THE FRONT FORK PROTECTOR GUIDE .......................... 3-28
CLEANING THE FRONT FORK OIL SEAL AND DUST SEAL ................ 3-28
AIR BLEEDING FROM FRONT FORK .................................................... 3-28
ADJUSTING THE FRONT FORK LEGS .................................................. 3-29
CHECKING THE SWINGARM OPERATION ........................................... 3-30
CHECKING THE REAR SUSPENSION ................................................... 3-30
ADJUSTING THE REAR SHOCK ABSORBER ASSEMBLY ................... 3-30
CHECKING THE TIRES ........................................................................... 3-32
CHECKING AND TIGHTENING THE SPOKES ....................................... 3-32
CHECKING THE WHEELS ...................................................................... 3-33

PRE-OPERATION INSPECTION AND MAINTENANCE
3-7
EAS1SL1067
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.
EAS1SL1068GENERAL INSPECTION AND MAINTENANCE
TIP
Perform usual maintenance enough so that, in the race course, a confirmation of that and simple set-
ting adjustments may only be left, in order to get enough time to use effectively.
ITEMinspectPage
CoolantCheck that coolant is filled up to the radiator cap.
Check the cooling system for leakage.3-8 – 10
FuelCheck that a fresh gasoline is filled in the fuel tank.
Check the fuel line for leakage.1-22
Engine oilCheck that the oil level is correct. Check the crank-
case and oil line for leakage.3-14 – 16
Gear shifter and clutchCheck that gears can be shifted correctly in order and
that the clutch operates smoothly.3-10 – 11
Throttle grip/Housing
Check that the throttle grip operation and free play
are correctly adjusted. Lubricate the throttle grip and
housing, if necessary.
3-11 – 12
BrakesCheck the play of front brake and effect of front and
rear brake.3-21 – 27
Drive chainCheck drive chain slack and alignment. Check that
the drive chain is lubricated properly.3-27
4-64 – 65
WheelsCheck for excessive wear and tire pressure. Check
for loose spokes and have no excessive play.3-32 – 33
SteeringCheck that the handlebar can be turned smoothly and
have no excessive play.3-33 – 34
Front forks and rear
shock absorberCheck that they operate smoothly and there is no oil
leakage.3-28 – 32
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.
—
Exhaust pipeCheck that the exhaust pipe is tightly mounted and
has no cracks.3-13 – 14
Rear wheel sprocketCheck that the rear wheel sprocket tightening bolt is
not loose.4-8 – 9
LubricationCheck for smooth operation. Lubricate if necessary. 3-12 , 3-34
Bolts and nutsCheck the chassis and engine for loose bolts and
nuts.1-25 – 26
Lead connectorsCheck that the AC magneto, ECU and ignition coil are
connected tightly.1-12 – 14
Settings
Is the machine set suitably for the condition of the rac-
ing course and weather or by taking into account the
results of test runs before racing? Are inspection and
maintenance completely done?10-1 – 8

CHASSIS
3-32
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Low compression dampingECA13590
NOTICE
Do not turn the adjuster forcibly beyond its
adjusting range.
1. Adjust:
• Low compression damping
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a. Turn the adjuster “1” in the direction of “a” or
“b” to make an adjustment.
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EAS1SL1107
CHECKING THE TIRES
1. Measure:
• Tire pressure
Out of specification  Regulate.
TIP
• Check the tire while it is cold.
• Loose bead stoppers allow the tire to slip off
its position on the rim when the tire pressure
is low.
• If the tire valve stem is found tilted, the tire is
considered to be slipping off its position. Cor
-
rect the tire position.
EAS1SL1108CHECKING AND TIGHTENING THE
SPOKES
1. Check:
• Spokes
Bend/damage  Replace.
Loose  Tighten.
TIP
A tight spoke will emit a clear, ringing tone; a
loose spoke will sound flat.
Direction “a”
Low compression damping force is in-
creased (suspension is harder).
Direction “b”
Low compression damping force is de-
creased (suspension is softer).
Low compression damping
Maximum
Turn it in finger-tight.
STD
Turn it out by 12 clicks.*
(USA)(CAN)
Turn it out by 10 clicks.*
(EUR)(JPN)(AUS)(NZL)(ZAF)
Minimum
Turn it out by 20 clicks.*
* With the adjuster fully turned in
1
a b
1ba
Tire pressure
100 kPa (1.0 kgf/cm2,15 psi)

TROUBLE SHOOTING
9-3
Fuel system
1. Throttle body
• Damaged or loose throttle body joint
2. Air filter
• Clogged air filter element
Chassis
1. Brake(s)
• Dragging brake
Electrical system
1. Spark plug
• Incorrect spark plug gap
• Incorrect spark plug heat range
2. Ignition system
• Faulty ECU
• Faulty coolant temperature sensor
EAS1SL1359OVERCOOLING
Cooling system
• Faulty coolant temperature sensor
EAS1SL1360POOR BRAKING PERFORMANCE
• Worn brake pad
• Worn brake disc
• Air in hydraulic brake system
• Leaking brake fluid
• Defective master cylinder kit
• Faulty brake caliper kit
• Faulty brake caliper seal
• Loose union bolt
• Damaged brake hose
• Oil or grease on the brake disc
• Oil or grease on the brake pad
• Incorrect brake fluid level
EAS1SL1361FAULTY FRONT FORK LEGS
Leaking oil
• Bent, damaged, or rusty inner tube
• Cracked or damaged outer tube
• Improperly installed oil seal
• Damaged oil seal lip
• Incorrect oil level (high)
• Loose damper rod assembly bolt
• Damaged damper rod assembly bolt copper
washer
• Cracked or damaged cap bolt O-ring
Malfunction
• Bent or damaged inner tube
• Bent or damaged outer tube
• Broken fork spring
• Bent or damaged damper rod
• Incorrect oil viscosity
• Incorrect oil level
EAS1SL1362UNSTABLE HANDLING
1. Handlebar
• Bent or improperly installed handlebar
2. Steering head components
• Improperly installed upper bracket
• Improperly installed lower bracket
(improperly tightened ring nut)
• Bent steering stem
• Damaged ball bearing or bearing race
3. Front fork leg (s)
• Uneven oil levels (both front fork legs)
• Unevenly tensioned fork spring (both front
fork legs)
• Broken fork spring
• Bent or damaged inner tube
• Bent or damaged outer tube
4. Swingarm
• Worn bearing or bushing
• Bent or damaged swingarm
5. Rear shock absorber assembly (-ies)
• Faulty rear shock absorber spring
• Leaking oil or gas
6. Tire (s)
• Uneven tire pressures (front and rear)
• Incorrect tire pressure
• Uneven tire wear
7. Wheel (s)
• Incorrect wheel balance
• Broken or loose spoke
• Damaged wheel bearing
• Bent or loose wheel axle
• Excessive wheel runout
8. Frame
• Bent frame
• Damaged steering head pipe
• Improperly installed bearing race

10
TUNING
CHASSIS........................................................................................................ 10-1
SELECTION OF THE SECONDARY REDUCTION 
RATIO (SPROCKET) .............................................................................. 10-1
DRIVE AND REAR WHEEL SPROCKETS SETTING PARTS ................ 10-1
TIRE PRESSURE..................................................................................... 10-2
FRONT FORK SETTING.......................................................................... 10-2
CHANGE IN AMOUNT AND CHARACTERISTICS OF FORK OIL.......... 10-2
SETTING OF SPRING AFTER REPLACEMENT .................................... 10-3
FRONT FORK SETTING PARTS............................................................. 10-3
REAR SUSPENSION SETTING .............................................................. 10-3
CHOOSING SET LENGTH ...................................................................... 10-3
SETTING OF SPRING AFTER REPLACEMENT .................................... 10-4
REAR SHOCK ABSORBER SETTING PARTS ....................................... 10-5
SUSPENSION SETTING (FRONT FORK)............................................... 10-6
SUSPENSION SETTING (REAR SHOCK ABSORBER) ......................... 10-7

CHASSIS
10-2
TIRE PRESSURE
Tire pressure should be adjusted to suit the
road surface condition of the circuit.
• Under a rainy, a muddy, a sandy, or a slippery
condition, the tire pressure should be lower
for a larger area of contact with the road sur
-
face.
• Under a stony or a hard road condition, the
tire pressure should be higher to prevent a flat
tire.
EAS1SL1369FRONT FORK SETTING
The front fork setting should be made depend-
ing on the rider's feeling of an actual run and
the circuit conditions.
The front fork setting includes the following
three factors:
1. Setting of air spring characteristics
• Change the fork oil amount.
2. Setting of spring preload
• Change the spring.
3. Setting of damping force
• Change the compression damping force.
• Change the rebound damping force.
The spring acts on the load and the damping
force acts on the cushion travel speed.
EAS1SL1370CHANGE IN AMOUNT AND CHARACTERIS-
TICS OF FORK OIL
Damping characteristic near the final stroke
can be changed by changing the fork oil
amount.
EWA1DX4001
WARNING
Adjust the oil amount in 5 cm3 (0.2 US oz,
0.2 Imp. oz) increments or decrements. Too
small oil amount causes the front fork to
produce a noise at full rebound or the rider
to feel some pressure on his hands or body.
Alternatively, too large oil amount will
cause the air spring characteristics to have
a tendency to be stiffer with the consequent
deteriorated performance and characteris
-
tics. Therefore, adjust the front fork within
the specified range.
EAS1SL1371
Standard tire pressure
100 kPa (1.0 kgf/cm2,15 psi)
Extent of adjustment
60–80 kPa (0.6–0.8 kgf/cm2, 9.0–
12 psi)
Extent of adjustment
100–120 kPa (1.0–1.2 kgf/cm2,
15–18 psi)
Standard oil amount
335 cm3 (11.33 US oz, 11.82
lmp.oz) (USA) (CAN)
355 cm3 (12.00 US oz, 12.52
lmp.oz) (EUR) (JPN) (AUS) (NZL)
(ZAF)
Extent of adjustment
300–365 cm3 (10.14–12.34 US
oz, 10.58–12.87 Imp. oz)
A. Air spring characteristics in relation to oil
amount change
B. Load
C. Stroke
1. Max. oil amount
2. Standard oil amount
3. Min. oil amount