Yamaha YFM400FAR Service Manual page 226

CARBURETOR
4.Check:
Piston valve 1
G
Scratches/wear/damage → Replace.
Rubber diaphragm 2
G
Tears → Replace.
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
Starter jet 6
G
Starter plunger 7
G
Bends/wear/damage → Replace.
Blockage → Blow out the jets with
G
compressed air.
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CARB