Yamaha YZ450F(B) 2012, Owner'S Service Manual, Page: 184 / 228

6-6
THROTTLE BODY
CHECKING THE INJECTOR
Replace the fuel injector with a
new one if you have dropped or im-
pacted it.
1. Check:
• Injectors
Damage
→
Replace.
CHECKING THE THROTTLE BODY
• Before removing the throttle
body, clean the area around the
throttle body to prevent dirt and
other foreign material from fall-
ing into the engine.
• If the throttle body is subject to
strong shocks or dropped during
cleaning, replace it.
• Do not use any caustic carbure-
tor cleaning solution.
• Do not directly push the throttle
valves to open them.
• Do not loosen the throttle valve
stopper screw "1", throttle valve
pulley nut "2", or throttle valve
screw "3". Otherwise, a loss of
performance may occur.
• Do not use compressed air to
clean the throttle body. Other-
wise, foreign material may ad-
here to the intake air pressure
sensor passage "a" and fuel in-
jector "b" in the throttle body.
1. Check:
• Throttle body
Cracks/damage
→
Replace the
throttle body as a set.
2. Check:
• Starter knob/ idle screw delivery
passages "a"
Obstructions
→ Blow out with
compressed air.
ASSEMBLING THE THROTTLE
BODY
1. Install:
• O-ring "1"
• Injector "2"
• Bolt "3"
Always use a new O-ring.
INSTALLING THE THROTTLE
BODY
1. Install:
• Throttle body joint "1"
• Throttle body "2"
• Face the slot "a" in the throttle body
joint toward the bottom of the vehi-
cle.
•Align the slot "a" on the throttle body
joint with the projection "b" on the
throttle body.
2. Install the water-resistant cover
"1" onto the throttle body.
CHECKING AND REPLACING THE
PROTECTOR
1. Check:
• Protector "1"
Wear/damage
→
Replace.
Affix the protector as shown.
Bolt (injector)
3 Nm (0.3 kg•m, 2.2
ft•lb)
Throttle body joint clamp
screw
3 Nm (0.3 m•kg, 2.2
ft•lb)