Polaris Predator 90 Service Manual

FUEL SYSTEM/CARBURETION
3.9
Air Jet
Throttle Valve
Jet Needle
By-pass
Pilot Outlet
Pilot Jet
Needle Jet
Main Jet
Clip Position
(Shown in #3)
1
2
3
4
5
Jet Needle “E” Clip Position
Leaner
Richer
Air
Box
Side
Engine
Side
General Carburetor Representation
MAIN SYSTEM
(3/4 to Full Throttle)
The main system is designed for delivering fuel
between low speed and high speed operation. This
system is made up of the jet needle, needle jet, and
main jet. The main system begins to take effect as
soon as there is enough air flow into the carburetor
venturitodraw fuel up throughthe main jet andneedle
jet assembly. This system works in conjunction with
the needle jet system.
During low speed driving, there is very little clearance
between the jet needle and the needle jet; therefore,
very little fuel from the main jet can pass between the
jet needle and the needle jet. As the throttle valve
opening is increased, the tapered jet needle is raised
farther out of the needle jet, allowing greater fuel flow.
Under full throttle opening, the cross sectioned area
of clearance between the jet needle and the needle jet
becomes greater than the cross sectioned area of the
main jet. Thus the main jet is now controlling the
amount of fuel flow.
Air Jet
Throttle Valve
Jet Needle
By-pass
Pilot Outlet
Pilot Jet
Needle Jet
Main Jet
Air
Box
Side
Engine
Side
General Carburetor Representation
FUEL DELIVERY (2 CYCLE)
The throttle opening chart below demonstrates
component relationship to fuel flow versus throttle
valve opening.
The pilot system’s main function is that of a low speed
jet. Its most effective range of fuel delivery is from idle
to approximately 3/8 throttle valve opening.
The throttle slide controls the rate of engine air by its
movement up and down in the carburetor venturi. At
small throttle openings the air flow is regulated chiefly
by the valve cutaway, with greatest effectiveness at
1/4 throttle opening. Throttle valves are numbered
1.0, 1.5, 2.0, etc., according to the size of the cutaway.
Decreasing the cutaway number will increase the
amount of fuel delivered in its effective range.
Enfocus Software - Customer Support

Polaris Predator 90 Specifications

General

Brand	Polaris
Model	Predator 90
Category	Offroad Vehicle
Language	English