2008 YAMAHA YZ450F check engine

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Page 51 of 188

YAMAHA YZ450F 2008  Owners Manual 3-5
ENGINE
ENGINE
CHECKING THE COOLANT LEVEL
Do not remove the radiator cap 
"1", drain bolt and hoses when the 
engine and radiator are hot. Scald-
ing hot fluid and steam may be 
blown out under pre

Page 52 of 188

YAMAHA YZ450F 2008  Owners Manual 3-6
ENGINE
Apply water on the radiator cap seal.
3. Radiator cap
2. Apply the specified pressure.
3. Inspect:
• Pressure
Impossible to maintain the speci-
fied pressure for 10 seconds
→
Replace.
C

Page 53 of 188

YAMAHA YZ450F 2008  Owners Manual 3-7
ENGINE
LUBRICATING THE THROTTLE
1. Remove:
• Cover (throttle cable cap) "1"
• Cover (grip cap) "2"
• Throttle grip cap "3"
2. Apply:
• Lithium soap base grease
On the throttle cable end "a

Page 54 of 188

YAMAHA YZ450F 2008  Owners Manual 3-8
ENGINE
CHECKING THE ENGINE OIL 
LEVEL
1. Stand the machine on a level sur-
face.
• When checking the oil level make 
sure that the machine is upright.
• Place the machine on a suitable 
stand.

Page 55 of 188

YAMAHA YZ450F 2008  Owners Manual 3-9
ENGINE
Replacement steps:
a. Remove the oil filter element cov-
er "1" and oil filter element "2".
b. Check the O-rings "3", if cracked 
or damaged, replace them with a 
new one.
c. Install the oi

Page 56 of 188

YAMAHA YZ450F 2008  Owners Manual 3-10
ENGINE
ADJUSTING THE VALVE 
CLEARANCE
• The valve clearance should be ad-
justed when the engine is cool to 
the touch.
• The piston must be at Top Dead 
Center (T.D.C.) on compression 
strok

Page 62 of 188

YAMAHA YZ450F 2008  Owners Manual 3-16
CHASSIS
CHECKING THE DRIVE CHAIN
1. Measure:
• Drive chain length (15 links) "a"
Out of specification
→Replace.
• While measuring the drive chain 
length, push down on the drive 
chain to i

Page 63 of 188

YAMAHA YZ450F 2008  Owners Manual 3-17
CHASSIS
CHECKING THE FRONT FORK
1. Inspect:
• Front fork smooth action
Operate the front brake and 
stroke the front fork.
Unsmooth action/oil leakage
→
Repair or replace.
CLEANING THE FRONT