Needle And Seat Leakage Test - Polaris SCRAMBLER 50 Service Manual

The jet needle and needle jet have an effective
operating range from approximately 1/8 to 7/8 throttle
opening. The amount of fuel delivered during this
range relies upon the jet needle clip position, as well
as the needle jet size and other specifications.
The main jet affects fuel delivery at 1/4 throttle and
consistently increases to full throttle opening.
THROTTLE OPENING - 2 Cycle
EFFECT
Throttle Valve Cut-Away
Jet Needle/Needle Jet
VENT SYSTEMS
The fuel tank vent line supplies atmospheric pressure
to the fuel in the tank. This line must be free of kinks
and restrictions to prevent lean mixture and possible
engine damage. All vent lines must be properly routed
to prevent damage to the line and to prevent
contaminants from entering the fuel system.
FLOAT HEIGHT
1. Invert the carburetor and remove float bowl.
2. Rest the float tongue lightly on the inlet needle
valve pin without compressing the spring.
3.10
FUEL SYSTEM/CARBURETION
3. The float should be parallel ±1 mm to the gasket
surface on all youth model ATV carburetors.
When setting the float, be sure inlet needle valve
spring is not compressed.
necessary, bend the tongue slightly.
Float
Gasket
Surface
Float Height:
Parallel to Gasket Surface ± 1mm
NEEDLE AND SEAT
LEAKAGE TEST
1. Install the float bowl. Invert the carburetor and
install a Mity-Vact (PN 2870975) to the fuel inlet
fitting. Apply 5 PSI pressure to inlet fitting. The
needle and seat should hold pressure indefinitely.
If not, inspect needle and seat and seat O-ring or
gasket.
If adjustment is
Parallel