Throttle valve....becz it's helpful to keep increase or maintain atomisation property means in your vehicle's the speed is main not load becz your heavy load vehicle work on compression cycle and carborator based mainly for light or speedy vehical where we use fuel...for making simple carborator complete assembly we need metering system is important for carborator becz it's control flow of fuel air ratio by accelerator and economiser is use to heat up or maintain viscosity even in summer or winter and choke is used to supply air means without ths all we can't make carborator but throttling is a additional feature make carborator more accurate.

Throttle valve is not added to a simple carburetor to make it complete.

A carburetor is a device used in internal combustion engines to mix air and fuel in the correct ratio for combustion. It consists of several systems that work together to ensure the engine receives the proper amount of fuel for efficient operation.

The main components of a carburetor include the float chamber, venturi, fuel jets, and throttle valve. These components work together to control the flow of air and fuel into the engine.

The purpose of the throttle valve is to regulate the amount of air entering the engine. It is typically located between the venturi and the intake manifold. By adjusting the position of the throttle valve, the driver can control the engine speed and power output.

However, in a simple carburetor, the throttle valve is not included. A simple carburetor is a basic design that does not have the added complexity of a throttle valve. It operates on a fixed fuel-air mixture and does not allow for variable engine speeds.

The absence of a throttle valve means that the engine speed and power output cannot be controlled by the driver. The engine will run at a fixed speed, typically determined by the design of the carburetor.

Simple carburetors are commonly used in small engines, such as those found in lawnmowers, chainsaws, and small motorcycles. These engines typically operate at a constant speed and do not require the variable control provided by a throttle valve.

In summary, the throttle valve is not added to a simple carburetor because it is not necessary for the basic operation of the engine. A simple carburetor operates on a fixed fuel-air mixture and does not allow for variable engine speeds.