Polaris 2012 Sportsman Forest 500 International, Service Manual

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4.10
CARBURATION AND FUEL SYSTEM
© Copyright 2011 Polaris Sales Inc.
9923412 - 2012 Sportsman 400/500 and EFI Tractor Service Manual
Float System
Fuel enters the float chamber (3) by means of the inlet pipe
and passage, through a 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 seat.
When fuel level is up in float chamber, floats are up and
needle valve remains pushed up against valve seat.
Under this condition, no fuel enters the float chamber. As
the fuel level falls, floats go down and needle valve
unseats itself to allow fuel into the chamber. In this
manner, the needle valve releases and shuts off fuel
alternately to maintain a constant fuel level inside the float
chamber.
Pilot Screw
The pilot system supplies fuel during engine operation
with the throttle valve closed or slightly opened. The fuel/
air mixture is metered by pilot screw and discharged into
the main bore through the pilot outlet.
Inlet
Pipe
1
2
3
4
CAUTION
The pilot screw is calibrated at the factory to meet
EPA / CARB regulations for air quality standards and
is sealed with a brass plug to prevent tampering.
Removal of the tamper proof plug is not permitted.
For service purposes, cleaning of the pilot circuit can
be done only by a certified repair shop to ensure air
quality standards are not exceeded.
Pilot Screw Location
Brass Plug Installed
Brass Plug Removed