Carburetor including one-piece fuel-metering insert

A carburetor for use with an internal combustion engine, the carburetor comprising:

• a body including an air/fuel passageway formed therein;
• a stem formed as part of the body and defining an inner wall;
• a throttle valve positioned in the air/fuel passageway;
• a fuel bowl coupled to the body;
• a fuel bowl chamber at least partially defined by the fuel bowl;
• a fuel-metering insert formed as a separate piece from the body and coupled to the body, the insert including
• a base having an outer surface having a shape that closely matches the shape of the inner wall;
• a first tower having a first end disposed within the air/fuel passageway and a second end coupled to the base;
• a main circuit passageway at least partially formed within the first tower and having a first end in fluid communication with the air/fuel passageway and a second end in fluid communication with the fuel bowl chamber, the main circuit passageway configured to carry fuel from the fuel bowl chamber to the air/fuel passageway during engine operation when the throttle valve is opened from the substantially closed position;
• a second tower having a first end coupled to the base and a second end spaced away from the base, wherein the first end of the first tower, the second end of the second tower, and the base are the sole engagement points between the insert and the body.