TROUBLESHOOTING
9-9
Front fork is soft
Fatigued or broken fork spring
Replace the fork spring.
Incorrect oil viscosity (low)
Change to recommended fork oil.
Incorrect oil level (low)
Adjust to the specified oil level.
Improperly adjusted spring pre-
load (soft)
Adjust the spring preload.
Improperly adjusted rebound
damping (soft)
Adjust the rebound damping.
Improperly adjusted compression
damping (soft)
Adjust the compression damping.
Leaking oil from front fork
Bent, damaged, or corroded inner
tube
Replace the inner tube.
Cracked or damaged outer tube
Replace the outer tube.
Improperly installed oil seal
Replace the oil seal.
Damaged oil seal lip
Replace the oil seal.
Incorrect oil level (high)
Adjust to the specified oil level.
Loose damper rod assembly bolt
Tighten the damper rod assembly
bolt to the specified torque.
Damaged damper rod assembly
bolt copper washer
Replace the damper rod assembly
bolt copper washer.
Cracked or damaged cap bolt O-
ring
Replace the cap bolt O-ring.
Rear suspension is hard
Bent or damaged rear shock
absorber rod
Replace the rear shock absorber.
Bent swingarm pivot shaft
Replace the swingarm pivot shaft.
Damaged or worn swingarm bear-
ing or bushing
Replace the swingarm bearing or
bushing.
Damaged or worn relay arm bear-
ing
Replace the relay arm bearing.
Damaged or worn connecting arm
bearing
Replace the connecting arm bear-
ing.
Improperly adjusted rear shock
absorber spring preload (hard)
Adjust the spring preload.
Improperly adjusted rear shock
absorber rebound damping (hard) Adjust the rebound damping.
Improperly adjusted rear shock
absorber compression damping
(hard)
Adjust the compression damping.
Symptom
Possible cause
Actions
Summary of Contents for YZ450F 2021
Page 6: ...EAM20162 YAMAHA MOTOR CORPORATION U S A YZ MOTORCYCLE LIMITED WARRANTY ...
Page 10: ......
Page 44: ...MOTORCYCLE CARE AND STORAGE 1 32 ...
Page 61: ...TIGHTENING TORQUES 2 16 ...
Page 62: ...CABLE ROUTING DIAGRAM 2 17 EAM20152 CABLE ROUTING DIAGRAM Frame and engine left side view ...
Page 64: ...CABLE ROUTING DIAGRAM 2 19 Frame and engine right side view ...
Page 66: ...CABLE ROUTING DIAGRAM 2 21 Handlebar front view ...
Page 68: ...CABLE ROUTING DIAGRAM 2 23 Frame and engine top view ...
Page 70: ...CABLE ROUTING DIAGRAM 2 25 Frame and battery top view ...
Page 72: ...CABLE ROUTING DIAGRAM 2 27 Rear brake right side view ...
Page 74: ...CABLE ROUTING DIAGRAM 2 29 ...
Page 112: ...ELECTRICAL SYSTEM 3 36 ...
Page 148: ...REAR BRAKE 4 34 system Refer to BLEEDING THE HYDRAULIC BRAKE SYSTEM on page 3 25 ...
Page 189: ...LUBRICATION SYSTEM CHART AND DIAGRAMS 5 3 1 Connecting rod 2 Oil nozzle 3 Crankshaft ...
Page 191: ...LUBRICATION SYSTEM CHART AND DIAGRAMS 5 5 1 Oil filter element 2 Oil pump 3 Oil strainer ...
Page 262: ...TRANSMISSION 5 76 ...
Page 272: ...WATER PUMP 6 9 ...
Page 282: ...THROTTLE BODY 7 9 ...
Page 289: ...IGNITION SYSTEM 8 6 ...
Page 290: ...ELECTRIC STARTING SYSTEM 8 7 EAM20143 ELECTRIC STARTING SYSTEM EAM30279 CIRCUIT DIAGRAM ...
Page 294: ...CHARGING SYSTEM 8 11 EAM20144 CHARGING SYSTEM EAM30282 CIRCUIT DIAGRAM ...
Page 297: ...CHARGING SYSTEM 8 14 ...
Page 298: ...FUEL INJECTION SYSTEM 8 15 EAM20145 FUEL INJECTION SYSTEM EAM30284 CIRCUIT DIAGRAM ...
Page 321: ...FUEL INJECTION SYSTEM 8 38 ...
Page 322: ...FUEL PUMP SYSTEM 8 39 EAM20146 FUEL PUMP SYSTEM EAM30287 CIRCUIT DIAGRAM ...
Page 352: ...SELF DIAGNOSTIC FUNCTION AND DIAGNOSTIC CODE TABLE 9 15 ...
Page 362: ...CHASSIS 10 9 ...
Page 364: ......
Page 366: ......
Page 368: ...YZ450FM 2021 WIRING DIAGRAM B2W 2819U 11_W D indd 2 2020 02 05 10 21 39 ...