2008 YAMAHA YZ450F Owners Manual

Page 73 of 188

YAMAHA YZ450F 2008  Owners Manual 4-5
RADIATOR
RADIATOR
REMOVING THE RADIATOR
Order Part name Qty Remarks
Drain the coolant.Refer to "CHANGING THE COOLANT" sec-
tion in the CHAPTER 3.
Seat and fuel tankRefer to "SEAT, FUEL TANK AND S

Page 74 of 188

YAMAHA YZ450F 2008  Owners Manual 4-6
RADIATOR
HANDLING NOTE
Do not remove the radiator cap 
when the engine and radiator are 
hot. Scalding hot fluid and steam 
may be blown out under pressure, 
which could cause serious injury. 
Whe

Page 75 of 188

YAMAHA YZ450F 2008  Owners Manual 4-7
CARBURETOR
CARBURETOR
REMOVING THE CARBURETOR
Order Part name Qty Remarks
Seat and fuel tank Refer to "SEAT, FUEL TANK AND SIDE 
COVERS" section.
Rear shock absorber Refer to "REAR SHOCK ABSORBER

Page 76 of 188

YAMAHA YZ450F 2008  Owners Manual 4-8
CARBURETOR
DISASSEMBLING THE CARBURETOR
Order Part name Qty Remarks
1 Carburetor breather hose 4
2 Valve lever housing cover 1
3 Screw (throttle shaft) 1
4 Throttle valve 1
5 Needle holder 1
6 Je

Page 77 of 188

YAMAHA YZ450F 2008  Owners Manual 4-9
CARBURETOR
19 Pilot jet 1
20 Starter jet 1
21 Push rod 1 Pull the push rod.
22 Throttle shaft assembly 1
23 Push rod link lever assembly 1
24 Pilot air jet 1
25 Cold starter plunger 1 Order Part n

Page 78 of 188

YAMAHA YZ450F 2008  Owners Manual 4-10
CARBURETOR
HANDLING NOTE
Do not loosen the screw (throttle 
position sensor) "1" except when 
changing the throttle position sen-
sor due to failure because it will 
cause a drop in engine perfor

Page 79 of 188

YAMAHA YZ450F 2008  Owners Manual 4-11
CARBURETOR
f. Recheck the float height.
CHECKING THE FLOAT
1. Inspect:
• Float "1"
Damage
→Replace.
CHECKING THE STARTER 
PLUNGER
1. Inspect:
• Cold starter plunger "1"
• Hot starter plun

Page 80 of 188

YAMAHA YZ450F 2008  Owners Manual 4-12
CARBURETOR
9. Install:
• Push rod "1"
While holding down the lever 1 "2", in-
sert the push rod farthest into the car-
buretor. 
10. Install:
• Starter jet "1"
• Pilot jet "2"
• Spacer "3