Yamaha WR426F(N) Owner's Service Manual page 358

CARBURETOR
2. Inspect:
Main jet 1
Pilot jet 2
Needle jet 3
Starter jet 4
Main air jet 5
Pilot air jet 6
Damage
Contamination
NOTE:
Use a petroleum based solvent for cleaning.
Blow out all passages and jets with com-
pressed air.
Never use a wire.
EC464210
Needle valve
1. Inspect:
Needle valve 1
Valve seat 2
Grooved wear a
Dust b and C
NOTE:
Replace the needle valve and valve seat as a
set.
EC464300
Throttle valve
1. Check:
Free movement
Stick
Insert the throttle valve 1 into the car-
buretor body, and check for free move-
ment.
EC464400
Jet needle
1. Inspect:
Jet needle 1
Bends/wear
Clip groove
Free play exists/wear
Clip position
Standard clip position:
No.4 Groove
4 - 12
ENG
Replace.
Clean.
Replace.
Clean.
Repair or replace.
Replace.
Replace.