Yamaha YZ450F(S) Owner's Service Manual page 262

CARBURETOR
2. Inspect:
Main jet 1
G
Pilot jet 2
G
Needle jet 3
G
Starter jet 4
G
Pilot air jet 5
G
Damage → Replace.
Contamination → Clean.
NOTE:
Use a petroleum based solvent for cleaning.
G
Blow out all passages and jets with com-
pressed air.
Never use a wire.
G
Needle valve
1. Inspect:
Needle valve 1
G
Valve seat 2
G
Grooved wear a → Replace.
Dust b → Clean.
EC464300
Throttle valve
1. Check:
Free movement
G
Stick → Repair or replace.
Insert the throttle valve 1 into the car-
buretor body, and check for free move-
ment.
EC464400
Jet needle
1. Inspect:
Jet needle 1
G
Bends/wear → Replace.
Clip groove
G
Free play exists/wear → Replace.
Clip position
G
Standard clip position:
No.4 Groove
*No.3 Groove
* Except for USA
4 - 12
ENG