High Atmospheric Pressure; Low Atmospheric Pressure - Polaris INDY TRAIL RMK Service Manual

Altitude Compensating Carburetor System (ACCS)
The Altitude Compensating Carburetor System (ACCS) is designed to automatically compensate for changes
in altitude. This allows the snowmobile to operate in changing elevations without having to change jets, although
extreme temperatures may require re-jetting for optimum performance. Refer to the jetting compensation chart
in the specifications sections.
A vacuum line is connected to the float bowl.
The ACCS valve is connected to this line via
the 4-way manifold. At low altitude the ACCS
valve supplies atmospheric pressure to the
vacuum line and the float bowl (see Ill. 1).
At high altitudes the bellows expand, moving
the plunger to the left and closing off some of
the passageways through the ACCS valve
(see Ill. 2). This prevents atmospheric pres-
sure from reaching the float bowl, allowing the
vacuum line to reduce the pressure in the float
bowl. This reduces the amount of fuel sup-
plied through the carburetor, preventing the
mixture from becoming too rich.
NOTE:The ACCS valve is calibrated specifi-
cally for the model it was intended. There are
no adjustments for the valve, and it should not
be tampered with in any way.
FUEL SYSTEM / CARBURETION

High Atmospheric Pressure-

Bellows compress
D
Fuel flow increases
D
Vacuum from
Venturi
Low Altitude / High
Atmospheric Pressure
ACCS System

Low Atmospheric Pressure-

Bellows expand
D
Fuel flow decreases
D
Vacuum from
Venturi
Plunger
High Altitude / Low
Atmospheric Pressure
ACCS System
To Float Bowls
Sealed
Plunger
Bellows
To Float Bowls
Sealed
Bellows
This
end
fixed
Ill. 1
This
end
fixed
Ill. 2
4.9