11
Use a socket to remove inlet needle and seat. Replace
with complete assembly.
FUEL INLET FITTING.
If necessary this fitting can
be removed by pulling and twisting. Be sure to install
in the same position as the original. When installing
fitting, insert tip into the carburetor body, then coat
the exposed portion of the shank with Loctite 242 Blue;
then press it in, until the shoulder contacts the carburetor
body.
THE PRIMER BULB (DIAPHRAGM CARBURETOR).
PUSH
RELEASE
with primers must have a check valve located in or
behind the fuel inlet fitting of the carburetor. This is
to prevent fuel from being forced back to the fuel line
and tank when priming.
Two types of check valves have been used. One is a
brass check valve pushed into the carburetor body
in the fuel inlet. The other is a teflon disc located in
the area under the fuel fitting. These two types of
check valves are not interchangeable.
To remove the brass type check valve, drill a 9/64'
(3.57 mm) hole through the center of the check valve,
making sure drill does not travel more than 1/8' (3.17
mm) into the body and damage the carburetor.
Turn a nut on to a 8-32 tap and slide a washer on
after it.
Turn the tap with nut and washer into the valve until
the tap begins to protrude through the valve when
viewed through the inlet needle and seat opening.
Turn the nut clockwise to pull the valve out from the
carburetor body.
The teflon disc-type can be cleaned by using low air
pressure forced into the inlet fitting. If service is required,
pull out inlet fuel fitting and replace the teflon disc.
Put a drop of oil on the disc and position in the cavity
of the carburetor. Replace fuel inlet fitting as outlined
in Fuel Inlet Fitting instructions.
BRASS
TEFLON
8-32 TAP
WASHER
PRESS IN PARTIALLY
THEN APPLY LOCTITE
"242 BLUE"
IDLE MIXTURE SCREW
MAIN MIXTURE SCREW
Pressing the bulb creates air pressure against the
diaphragm. Fully depress primer bulb with your thumb,
making sure that the vent hole in bulb is covered.
Release and allow bulb to return to original position.
As the diaphragm lifts, the inlet needle is lifted off its
seat and the fuel within the reservoir is fed up through
the passages into the air horn. A one-way valve in the
body prevents the fuel from being forced back into
the fuel tank.
CARBURETOR CHECK VALVE.
Diaphragm carburetors
Summary of Contents for AH520 -
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