Jet Needle / Needle Jet (3/8 - 3/4 Throttle); Main System (3/4 To Full Throttle) - Polaris PREDATOR 50 2009 Manual

FUEL SYSTEM

Jet Needle / Needle Jet (3/8 - 3/4 Throttle)

The jet needle and needle jet have the most effect between 3/8
and 3/4 throttle opening. Some mixture adjustment can be
accomplished by changing the location of the "E" clip on the
needle. Moving the clip down raises the needle in the jet passage
and richens the mixture. Moving the clip up lowers the needle
in the jet passage and leans the mixture. Letter and number codes
are stamped into the needle and the jet indicating sizes and
tapers of each.
General Carburetor Representation
Clip Position
(Shown in #3)
Air Jet
Air
Box
Side
Leaner
Richer
Jet Needle "E" Clip Position
4.8
Throttle Valve
Jet Needle
By-pass
Pilot Outlet
Engine
Side
Pilot Jet
Needle Jet
Main Jet
1
2
3
4
5

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
venturi to draw fuel up through the main jet and needle 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.
General Carburetor Representation
Air Jet
Air
Box
Side
Throttle Valve
Jet Needle
By-pass
Pilot Outlet
Engine
Side
Pilot Jet
Needle Jet
Main Jet