2001 Polaris Sportsman 400-500 DUSE and H.O. Service Manual, Page 157Get this manual
FUEL SYSTEMCARBURETION
PILOT (IDLE AND SLOW) SYSTEM
This system supplies fuel during engine operation with throttle valve closed (1) or slightly openedThe fuel from float chamber (2) is metered by pilot jet (3) where it mixes with air coming in through pilot air jet (4)The mixture then goes up through pilot passage to pilot screw (5)A part of the mixture is discharged into the main bore out of bypass ports (6)The remainder is then metered by pilot screw and discharged into the main bore through pilot outlet (7)