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What does a lawnmower carburetor look like?

The carburetor is a fundamental component responsible for providing the correct air-fuel mixture for the lawnmower engine combustion chamber. Termed as the machine’s lungs, they take in the fresh air, so they are situated at the most suitable position. The carburetor has a complex shape with several connections. These include the air intake, fuel lines, and exit lines to bring the mixture to the engine. It deals with the combustible mixture, also known as a charge. It often has a bowl-shaped body to incorporate the machine’s pressure changes. A carburetor is a part that is generally bolted to the side or top of a lawnmower engine, depending on the manufacturer. It helps to know the details about the shape and different carburetor components to understand the device better. This article will guide you about the carburetor components, shapes, and structure to better picture how a carburetor looks and works.

What does a lawnmower carburetor look like:

Most carburetors look very similar, a small metal component with levers and springs and a characteristic bowl shape under the carburetor body. Some carburetors do not use a conventional gas bowl or float bowl at the bottom. Riding lawnmowers with a bigger engine use bigger carburetor components than a push mower that uses a more compact one.

This blog post will give you an insight into the individual components and their shapes. You will get an understanding of the complete carburetor shape and its design,

What components does a lawnmower carburetor have?

Although small carburetors are crucial to your mower engine’s efficient performance. A lawnmower engine requires a mixture of fuel and air to run. The fuel-to-air ratio is known as the Air-Fuel ratio (AFR) that is 14.7 to 1 generally for an internal combustion engine as in a lawnmower. The carburetor is tasked with maintaining this ratio. It has to make the mixture rich or lean as the mower requires power. The bowel or bean-shaped carburetor has one side dedicated to taking in air. The mid has the mixing components and fuel lines. At the same time, the end part carries the charge. Stay tuned as we take you through the components that constitute a carburetor. This will help you imagine the shape of a carburetor.

We will now look into the lawnmower carburetor in more detail:

  1. Basic carburetor design
  2. Carburetor’s bowl and float
  3. Choke plate and Throttle plate  
  4. Main jet and idle jet
  5. Riding vs. push mowers carburetors
  6. Size comparison with other mower parts

The lawnmower carburetor in more detail:

We will discuss the lawnmower carburetor in more detail. Look at the various parts, see the difference between riding and push lawnmower carburetors. And finally, look at the size of the carburetor compared with other lawnmower components.

● 1: Basic lawnmower carburetor design

The carburetors of a lawnmower comprise of a few key parts:

  • carburetor bowl
  • float
  • choke plate
  • lever
  • throttle plate
  • butterfly lever
  • main jet
  • idle jet
  • pilot jet screw

To give an overall picture, the jets are responsible for fuel intake. The levers and plates mix the fuel, and the screws control the flow. Whether the mower requires more or less power, the carburetor is there to adjust the charge accordingly.

● 2: Lawnmower Carburetor’s bowl and float

Carburetor’s bowl, also known as a float bowl, is situated at the bottom with a single screw that attaches it inside the carburetor’s body. It is simply a metal bowl that looks like a round tray. This float bowl holds the fuel and gives the constant supply of fuel to the carburetor mixture on demand. It also has a drain bolt or screw through which you can drain the gasoline without dismantling the whole machinery.

The float is fastened to the carburetor with a pin. It is simply a round-shaped, small sealed vessel made of brass or plastic attached with a metering needle. A carburetor body attaches them both through a hinge pin. Removing the float or hinge pin will release the float and needle. It maintains the constant level of fuel in the float bowl.

● 3: Lawnmower Choke plate and Throttle plate 

A choke lever is a black plastic valve that functions to close or open the engine’s fuel opening when you start it. It can be primarily seen from one side of the engine as a round metallic plate called a choke plate. As the piston comes down on the intake stroke with this choke plate closed, the carburetor creates a little suction. This suction further helps to suck more fuel from the main jet.

The throttle plate is just a metallic round plate fitted on another side of the carburetor opposite the choke plate. It is a plastic valve, black in color, controlled by a throttle butterfly valve, which controls your engine’s air intake.

● 4: Main Lawnmower carburetor jet and idle jet

There is a black screw, known as an idle screw or a throttle backstop screw, situated above the pilot jet connected to your throttle lever. It sets the fuel mixture at optimum when your throttle will be set at the closed position. It also sets your idle state of the engine at higher RPMs depending on the mower’s condition.

Below this, you can view the pilot jet, also known as idle jet. You can see a couple of little O-rings on it that cover the hole inside that jet. At the bottom, a brass tip is connected with the hole that covers its base. It sets the amount of fuel going into your engine when your mower is idling, i.e., no-load condition. All the lawnmowers do not have this type of pilot jet, but the assembly is somewhat the same; the material can differ.

The main jet is just screwed into the long base tube attached beneath the carburetor. Some carburetors have this jet adjustable, and some have this fixed in that long distribution tube. This controls the main fluid flow.

Now that you know the individual parts and their functions, you can get a picture of what the carburetor looks like. The following youtube video is about adjusting and tuning the carburetor and its components. You can use it to visualize the size and shape of a carburetor and its insides:

● 4: Riding and push lawnmower carburetor

Most carburetors look very similar, with small metal components having levers and springs and the characteristic bowl shape under the carburetor body. Having a carburetor in hand brings your notice towards a large opening at the front for air intake, a central core carrying all internal components, and a backport from where the charge is forced through the venture. The carburetor has a tubular end; atomized fuel is being extracted from the bowl through this end. What I have labeled is the standard type carburetor, but not all carburetors look like this. Its shape and size vary from model to model to some extent.

As the riding lawnmowers are bigger and demand heavy combustion during the mowing process, so its carburetors components are bigger. Moreover, they are concealed under the hood so that you can imagine a carburetor with a larger intake at the front. Further, you can also visualize a compact shape, tighter connections, and shorter tubing.

The push mowers are primarily used for small yards. It has a compact carburetor with a smaller intake and smaller components.

● 5: Carburetor Size comparison with other mower parts

The carburetor’s size is an indication of the mower’s power. Their shape defines the type of mower. A comparison might be able to give you further insight. You will notice a large bowl at the top of the mower body, called the gas tank. Beneath it will be the carburetor, mainly central in shape with extruded tubular sections for intake. The engine along it will almost be comparable in size to the carburetor.

Frequently asked questions

1. How do you locate a lawnmower carburetor?

A lawnmower carburetor breathes behind the air filter and is often hidden from view. So first, we will locate the air intake or filter. Figure out for a round or square-shaped filter casing positioned on the top or side of the mower engine; it has holes or slots in the top. The case is mounted to the carburetor by fasteners or screws and holds a paper or foam filter. When you look at the air filter housing, and for most mowers, you’ll see a standard kind carburetor. A standard carburetor will have a metal bowl, which is easy to identify because of its shape.

2. What is the most crucial component of a lawnmower carburetor?

The most important components of your lawnmower carburetors are the main jet and accelerator pump. Your main jet meters the amount of fuel going into the distribution tube. It is typically mounted at the inlet of the distribution tube, which carries the fuel from the float bowl. Some carburetors also have holes in that tube from where the small jets of fuel enter the distribution tube and then to the main jet. The accelerator pump injects fuel into the inlet air when the throttle is opened suddenly. This provides the thrusts to the fuel. It may not be present in every carburetor; it mainly depends on the needs.

3. How is a carburetor of a lawnmower different from an automobile carburetor?

It is not necessarily the shape or working, but the lawnmower engine and automobile engine size differ significantly. Car engines require a higher intake of air and fuel to operate the vehicle at higher RPMs. It is designed to have excess gas in the fuel bowls and the main jet. Hence, an automobile’s carburetor’s components are larger than the lawnmower carburetor’s components.

Final remarks:

Generally, the engine cranking, rough running, and stalling problems are primarily linked to a defective carburetor. Significant issues on carburetor are caused due to numerous obstacles from dust, paint, and gasoline residues. Finding the cause of a problem is easier if you have some knowledge of the carburetor’s shape and size. Knowing the components, their orientation, and attachment, and their working, one can more easily check the carburetor.