Yamaha YZ250F(W) Owner's Service Manual page 284

CARBURETOR
HANDLING NOTE
CAUTION:
Do not loosen the screws (throttle position
sensor) 1 except when changing the throt-
1
tle position sensor due to failure because it
will cause a drop in engine performance.
REMOVAL POINTS
Pilot screw
1. Remove:
• Pilot screw 1
NOTE:
To optimize the fuel flow at a small throttle
opening, each machine's pilot screw has been
individually set at the factory. Before removing
the pilot screw, turn it in fully and count the
number of turns. Record this number as the
factory-set number of turns out.
INSPECTION
Carburetor
1. Inspect:
• Carburetor body
Contamination → Clean.
NOTE:
• Use a petroleum based solvent for cleaning.
Blow out all passages and jets with com-
pressed air.
• Never use a wire.
4 - 12
ENG