Yamaha YFM45FAR Service Manual page 249

CARBURETOR
5.Check:
Vacuum chamber cover 1
G
Spring 2
G
Cracks/damage → Replace.
6.Check:
Diaphragm (coasting enricher) 1
G
Spring 2
G
Cover 3
G
Tears (diaphragm) /damage → Replace.
7.Check:
Jet needle 1
G
Main jet 2
G
Needle jet 3
G
Pilot air jet 4
G
Pilot jet 5
G
Pilot screw 6
G
Starter jet 7
G
Starter plunger 8
G
Bends/wear/damage → Replace.
Blockage → Blow out the jets with
G
compressed air.
8.Check:
Free movement (piston valve)
G
Sticks → Replace the piston valve guide and
the piston valve.
Insert the piston valve into the carburetor
body, and check for free movement.
9.Check:
Free movement (throttle valve)
G
Sticks → Replace.
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CARB