2008 Polaris ATV Sportsman 300 400 H.O. Service Manual, Page 101Get this manual
FUEL SYSTEM Float System
Fuel enters the float chamber (3) by means of the inlet pipe and passage, through screen on the back of the inlet needle seat (4), and around the inlet needle (2)As the fuel fills the float chamber, the float (1) rises and forces the inlet needle against the seat, shutting off the orifice in the seatWhen fuel level is up in float chamber, floats are up and needle valve remains pushed up against valve seatUnder this condition, no fuel enters the float chamberAs the fuel level falls, floats go down and needle valve unseats itself to allow fuel into the chamberIn this manner, the needle valve releases and shuts off fuel alternately to maintain constant fuel level inside the float chamber