2014 YAMAHA YZ450F air suspension

CHASSIS SPECIFICATIONS
2-10
Compression damping adjusting positions
* Position in which the adjuster is turned in finger tight
Minimum 20 click (s) out*
Standard 9 click (s) out* (USA) (CAN)
8 click (s) out* (EUR) (JPN) (AUS) NZL) (ZAF)
Maximum (hard) Fully turned in
Rear suspension
Type Swingarm (link suspension)
Spring/shock absorber type Coil spring/gas-oil damper
Rear shock absorber assembly travel 132.0 mm (5.20 in)
Spring free length 275.0 mm (10.83 in)
Spring rate K1 58.00 N/mm (5.91 kgf/mm, 331.18 lbf/in) (USA) 
(CAN)
56.00 N/mm (5.71 kgf/mm, 319.76 lbf/in) (EUR) 
(JPN) (AUS) (NZL) (ZAF)
Spring stroke K1 0.0–150.0 mm (0.00–5.91 in)
Optional spring available Yes
Enclosed gas/air pressure (STD) 980 kPa (9.8 kgf/cm2, 139.4 psi)
Spring installed length
Minimum Position in which the spring is turned in 1.5 mm 
(0.06 in) from its free length.
Standard Position in which the spring is turned in 10 mm 
(0.39 in) from its free length.
Maximum Position in which the spring is turned in 18 mm 
(0.71 in) from its free length.
Rebound damping adjusting positions
* Position in which the adjuster is turned in finger tight
Minimum 30 click (s) out*
Standard 14 click (s) out* (USA) (CAN)
12 click (s) out* (EUR) (JPN) (AUS) (NZL) 
(ZAF)
Maximum Fully turned in
Compression damping adjusting positions 
(for fast compression damping)
* Position in which the adjuster is turned in finger tight
Minimum 2 turn (s) out*
Standard 1-1/2 turn (s) out* (USA) (CAN)
1-1/8 turn (s) out* (EUR) (JPN) (AUS) (NZL) 
(ZAF)
Maximum Fully turned in
Compression damping adjusting positions 
(for slow compression damping)
* Position in which the adjuster is turned in finger tight
Minimum 20 click (s) out*
Standard 12 click (s) out* (USA) (CAN)
10 click (s) out* (EUR) (JPN) (AUS) (NZL) 
(ZAF)
Maximum Fully turned in
Swingarm
Swingarm end free play limit (radial) 1.0 mm (0.04 in)
Swingarm end free play limit (axial) 0.2–0.9 mm (0.01–0.04 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

CHASSIS
3-29
3. Tighten:
• Air bleed screw
EAS1SL1103ADJUSTING THE FRONT FORK LEGSEWA32D1006
WARNING
• Always adjust the left and right front forks
evenly. If this is not done, the vehicle may
have poor stability.
• Securely support the vehicle so that there
is no danger of it falling over.
Rebound damping forceECA13590
NOTICE
Do not turn the adjuster forcibly beyond its
adjusting range.
1. Adjust:
• Rebound damping force
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Turn the adjuster “1” in the direction of “a” or
“b” to make an adjustment.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
Compression damping forceECA13590
NOTICE
Do not turn the adjuster forcibly beyond its
adjusting range.
1. Adjust:
• Compression damping force
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Turn the adjuster “1” in the direction of “a” or
“b” to make an adjustment.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS1SL1104
Air bleed screw
1.3 Nm (0.13 m·kgf, 0.94 ft·lbf)
Direction “a”
Rebound damping force is increased
(suspension is harder).
Direction “b”
Rebound damping force is decreased
(suspension is softer).
Rebound damping force
Maximum
Turn it in finger-tight.
STD
Turn it out by 8 clicks.*
Minimum
Turn it out by 20 clicks.*
* With the adjuster fully turned in
T R..
1
Direction “a”
Compression damping force is in-
creased (suspension is harder).
Direction “b”
Compression damping force is de-
creased (suspension is softer).
Compression damping force
Maximum
Turn it in finger-tight.
STD
Turn it out by 9 clicks.*
(USA)(CAN)
Turn it out by 8 clicks.*
(EUR)(JPN)(AUS)(NZL)(ZAF)
Minimum
Turn it out by 20 clicks.*
* With the adjuster fully turned in
1
a
b
a b
1

FRONT FORK
4-41
5. Check:
• Base valve “1”
Wear/damage  Replace.
Contamination  Clean.
• O-rings “2”
Wear/damage  Replace.
• Base valve bushing “3”
Wear/damage  Replace.
• Spring “4”
Damage/fatigue  Replace the base valve.
• Air bleed screw “5”
Wear/damage  Replace.
6. Check:
• Contacting surface “a”
Wear/damage  Replace.
7. Check:
• Adjuster “1”
• O-rings “2”
Wear/damage  Replace.
EAS1SL1169ASSEMBLING THE FRONT FORK LEGSEWA13660
WARNING
• Make sure the oil levels in both front fork
legs are equal.
• Uneven oil levels can result in poor han-
dling and a loss of stability.
TIP
• When assembling the front fork leg, be sure to
replace the following parts:
• Inner tube bushing
• Outer tube bushing
• Oil seals
• Copper washers
• Before assembling the front fork leg, make
sure that all of the components are clean.
1. Stretch the damper assembly fully.
2. Fill:
• Damper assembly
ECA14210
NOTICE
• Be sure to use the recommended oil. Other
oils may have an adverse effect on front
fork performance.
• When disassembling and assembling the
front fork leg, take care not to allow any
foreign material to enter the front fork.
3. After filling, pump the damper assembly “1”
slowly up and down (about 200 mm (7.9 in)
stroke) several times to bleed the damper
assembly of air.
TIP
Avoid excessive full stroke. A stroke of 200 mm
(7.9 in) or more will cause air to enter. In this
case, repeat the steps 1 to 3.
21
New
New
New
2
21 543
a
New
Recommended oil
Suspension oil S1
Standard oil amount
204 cm3 (6.90 US oz, 7.20
Imp.oz)
New
1
2