TROUBLESHOOTING
9-3
Excessive noise from engine
—
Worn camshaft lobe
Replace the camshaft.
Water or foreign material in fuel,
degraded fuel
Change fuel.
Contaminated throttle body or
clogged internal passage
Clean the throttle body.
Incorrectly adjusted throttle cable
Adjust the throttle grip free play.
Incorrectly adjusted idling speed
(idle screw)
Adjust the idle screw.
Incorrect throttle position sensor
angle
Adjust the throttle position sensor
angle.
Incorrect acceleration position
sensor angle
Adjust the acceleration position
sensor angle.
Faulty ECU
Replace the ECU.
Clogged vacuum hose
Clean the vacuum hose.
Cracks and damage in vacuum
hose
Replace the vacuum hose.
Damaged throttle body joint
Replace the throttle body joint.
Loose throttle body joint
Tighten the throttle body joint bolts
to the specified torque.
Clogged air filter element
Clean or replace the air filter ele-
ment.
Incorrect oil level (high)
Adjust the oil level to the specified
level.
Symptom
Possible cause
Actions
Noise heard from around cylinder
head
Incorrect valve clearance (too
wide)
Adjust the valve clearance.
Fatigued or broken valve spring
Replace the valve spring.
Worn or damaged camshaft lobe
Replace the camshaft.
Worn or damaged valve lifter
Replace the valve lifter and cylin-
der head as a set.
Worn or damaged camshaft jour-
nal
Replace the camshaft.
Worn or damaged cylinder head
(camshaft journal)
Replace the cylinder head.
Noise heard from around timing
chain
Worn or damaged timing chain
Replace the timing chain and cam-
shaft sprocket as a set.
Worn or damaged camshaft
sprocket
Replace the timing chain and cam-
shaft sprocket as a set.
Worn or damaged timing chain
guide
Replace the timing chain guide.
Cracked, damaged, or faulty tim-
ing chain tensioner
Replace the timing chain ten-
sioner.
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 ...