Service Manual

As the throttle plate is opened to compensate for engine
load, the main discharge tube becomes the main source of
fuel. Opening the' throttle plate increases the flow of air
through the venturi and strengthens the low pressure area
at the main discharge tube. Fuel discharge increases at
the main discharge tube as it decreases from the pilot
system. Air is drawn from the air correction jet, through
holes along the length of the main discharge tube. This
pre-mixes air with the fuel before
it enters the carburetor
bore for more efficient atomizing of the fuel. See Figure
13.
SYSTEM
Figure 13
Carburetor Removal
1. Remove the fuel from the tank as described in the
Maintenance Section on page
16.
2. Remove the three 5/16" hex, washer head shoulder
screws retaining the air cleaner to the carburetor.
Take care not to lose the cork gasket that seals
between the air cleaner body and the carburetor. See
Figure
14.
Figure 14
3. Disconnect the choke over-center spring. Note the
position of the spring for correct assembly. See
Figure
15.
Figure 15
4. Remove the two 3/8" hex, washer head screws that
retain the carburetor, the insulator gasket, and engine
block. See Figure
16.
Figure 16
5. Have a rag ready to absorb a small amount of spilled
gasoline. Pull the carburetor away from the engine.
Twist the carburetor to unhook the carburetor from the
governor link rod. As the carburetor is tilted, fuel that
is in the fuel bowl may leak out the bowl vent tube.
6. Hold the carburetor over a drain pan and use a 1/2”
wrench to loosen the bowl nut. Allow the remaining
fuel
in the bowl to drain into the pan. Tighten the bowl
nut.
20 GTS 150