Yamaha YZF-R1 1998 Service Manual page 255

CARBURETORS
8. Check:
• piston valve 1
Damage/scratches/wear → Replace.
• piston valve diaphragm 2
Cracks/tears → Replace.
9. Check:
• vacuum chamber cover 1
• piston valve spring 2
• jet needle holder 3
• jet needle spring 4
Cracks/damage → Replace.
10.Check:
• jet needle kit 1
• main jet 2
• main jet holder 3
• pilot jet 4
• pilot screw 5
• starter plunger 6
• pilot air jet 7
Bends/damage/wear → Replace.
Obstruction → Clean.
Blow out the jets with compressed air.
11.Check:
• piston valve movement
Insert the piston valve into the carbu-
retor body and move it up and down.
Tightness → Replace the piston valve.
12.Check:
• fuel feed pipes 1
• pipes 2
• hose joints 3
Cracks/damage → Replace.
Obstruction → Clean.
Blow out the pipes with compressed
air.
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CARB