A carburetor is a device which helps in mixing fuel and air together for facilitating internal combustion inside an internal combustion engine. This device passes the mixture of fuel and air to the intake manifold (a device delivering air/fuel mixture to the cylinders) of an internal combustion engine. While the earlier versions of carburetors used to do this merely by allowing air to pass over the fuel surface, the advanced version of carburetors dispenses a metered amount of fuel into the stream of air to achieve this purpose.
An engine needs the mixture of fuel and engine to drive a vehicle. Now, exactly how much air and fuel an engine requires to move a vehicle varies every moment depending on several factors like the speed and how long the vehicle is running. Carburetors are the devices which help in mixing air-fuel in an engine to help it work efficiently. In other words, a carburetor is a clever gadget which mixes the fuel and air in correct proportions as per the demand of the engine. It is a tube which lets air and fuel pass into the engine through valves, mixes them together in different quantities to meet the engine requirements in varied driving conditions.
Meaning Of Carburetor
The carburetor is a word in the English language which is taken from the French word "Carbure'' which means ''Carbide''. In the French language, “Carburetor” means “to blend something with carbon”. In the same line, the word carburetor in English etymologically means “to raise the carbon content, particularly of a fluid”.
Components Of a Carburetor
Though the components of carburetors vary according to their types, the modern spray carburetors have certain components in common which are as follows:
- venturi (an air passage)
- throttle linkage
- a throttle valve
- a power valve or metering/step-up rod
- a choke
- an accelerator pump
- a float chamber
- a bowl
- adjustment screws, etc
How Does a Carburetor Work?
When fuel mixes with air it turns into power which then burns in metal cylinders inside the engines and the energy hence generated drives most of the vehicles that travel on land, water, or sky. A carburetor is the device which mixes the fuel with air in correct proportion as per the need of the engine. Hence, a carburetor is nothing but an air-fuel mixing device placed inside the engine of a vehicle. In short, it can be said that a carburetor is a machine which adds fuel to air to make a mixture which is just perfect for burning in the cylinders present inside the engines. Though in modern vehicles carburetors are often replaced by electronically-controlled fuel-injection systems which make use of less fuel causing less pollution, carburetors are still present in motorcycles and old cars. The working principle of a carburetor is detailed right here.
In a carburetor, there are two spinning valves which are present just above and below the venturi. The top valve which is known as the choke is responsible to handle or regulate the amount of air that should flow inside the carburetor. When the valve is closed, less amount of air can pass in and as a result, the venturi will suck in more fuel providing a mixture rich in fuel to the engine. This thing is specifically helpful when the engine has just started or the car is cold and needs some time to get heated up. The second valve present in the carburetor is the throttle. When the throttle is wide open, more amount of air passes through the carburetor as a result of which the carburetor can drag more fuel from the pipe to the sides resulting the engine to release more energy and power enabling the car to go faster. This is the reason a car accelerates when the throttle is opened. In fact, the functioning of a throttle can be compared to blowing a campfire to help it burn quickly.
Types of Carburetor
Based on the direction of the flow of air there are 3 different types of carburetors. The types of the carburetors are as follows:
In the updraught carburetor air goes inside through the bottom and passes through the top in a way that the direction of the flow is upwards. The main disadvantage of this type of carburetor is that the mixing tube of this machine being very small, it is not capable of supplying mixture to the engine at the required speed when the vehicle is on high speed. With an intent to overcome this drawback of the updraught carburetor, the downdraught carburetor has been opted for.
The downdraught carburetor is placed at a higher level than the inlet manifold and as a result, in this type of carburetor, the air and the mixture flow a downward course. In such carburetors, the mixing tube and throat are largely resulting the engine speed to be high even when the vehicle is running at a high speed.
Constant Choke Carburettor:
In this type of carburetor, a consistency is always maintained for fuel and air flow areas so that they remain constant. However, the difference between pressure or depression which triggers the flow of air and fuel varies according to the need or requirement of the engine. Zenith and Solex carburetors are constant choke carburetors in nature.
Constant Vacuum Carburettor:
A constant vacuum carburetor which is also called as a variable choke carburetor, is a carburetor where the areas of fuel and air flow are different according to the requirement of the engine. However, in the process, the maintained vacuum is always the same. The Carter and S.U. carburetors are examples of constant vacuum carburetor.
Multiple Venturi Carburetor:
A multiple venturi carburetor is a carburetor which makes use of double or triple venturi. In this carburetor, the boost venturi is concentrically positioned within the main venturi and its discharge edge is located at the main venturi's throat. As a result, just a fraction of the total air passes through the boost venturi.
A bike carburetor is a vital component of a bike engine since it controls the ratio of the fuel and air mixture going inside the engine which is responsible for its movement. Since the cost of fuel injector technology is more than carburetors, most of the bikes in India still make use of carburetors. Mechanical carburetors, constant velocity carburetors or CV, and downdraft carburetors are the most common types of carburetors used in the motorbikes across the globe. In India, many bikes manufactured by Honda, Hero, and Bajaj are still using carburetors.
Solex carburetor is a type of downdraft carburetor which is widely used in top European automobiles such as Porsche, Rolls-Royce, Mercedes Benz, and Volkswagen. This special type of carburetor is designed to provide rich fuel and air mixture when the engine is started. While supplying the mixture it gradually slows down until the engine attains its normal speed. Fiat is the most popular brand manufactured in India which uses Solex carburetors. The Fiat car is well-known for its easy and quick start in cold weather conditions and this is attained due to the Solex carburetors.
Why is it important to clean the carburetor regularly?
The carburetor, being the most vital part of an engine, is extensively used by the engine. As a result, over the years, the carburetors and the choke valves become clogged with dirt, varnish, gum etc. which affect the performance of the engine. Hence, it is important to clean the carburetor at regular intervals to maintain the engine health and power up the performance.
What is a carburetor cleaner?
As the name suggests, a carburetor cleaner is a tool which helps to clean the carburetor and make it free from dirt and grease. It can be used to remove the accumulated deposits and debris from the outside and inside of the carburetor for improving the performance of the engine along with providing fuel efficiency. Such cleaners help to clean all non-painted metal parts and surfaces as well. A carburetor spray cleaner is the most effective means of cleaning the carburetor.
The carburetor needs to be cleaned carefully as all the parts of the engine have to be removed before the process and assembled again after the cleaning is over. Hence, it is important to know the carburetor cleaning process thoroughly before starting it. Here is the step-by-step process to clean a carburetor with the help of a spray cleaner:
Directions to use:
When the engine is off and cool
At first, remove the air cleaner unit by unscrewing the wing nut and clean the carburetor from outside and all other linkages. Next, you have to spray the carb cleaner on top of the carburetor in a way that it covers all reachable parts. Wait for some time until the cleaner loosens all the dirt and grease accumulated on the carburetor. After that clean the surface with a towel.
For cleaning the manifold heat control, spray the cleaner on the open ends of the cool heat riser shaft. When done, wait till the cleaner goes inside and cleans the dirt and deposits. Move the counterweight up and down until it becomes completely clog-free and can move freely.
When the engine is running
At first, start the engine. Then spray the cleaner down the throat, all around the outer surface of the carburetor, and on both the ends of the choke valve shaft while moving the choke using your hand. In order to clean the deposits from the throttle plate area, spray the cleaner adequately down and around the throat of the carburetor. Make sure not to spray under the throttle plate. If the choke is sticky, remove the choke cover and then spray the cleaner. While cleaning the PVC valve, disconnect the crankcase side and then spray the cleaner into the exposed end of the valve while moving the plunger back and forth.
After spraying, wait for sometime and turn off the engine. Spray again generously on the outside as well as the inside of the carburetor. Then start the engine and repeat the process. Once done, clean the grease on the accessible parts of the carburetor with a towel. Once you are done with cleaning, reinstall the parts.
Tips to remember while cleaning the carburetor
- Keep the cleaner away from electrical connections and battery terminals
- Keep your hand upright while spraying the can
What are the symptoms of a failing carburetor?
Backfiring and overheating are the most vital symptoms of a failing carburetor. Carburetors having issues delivers a lean mixture which don’t have sufficient fuel and this eventually lead to backfiring or overheating of the engine. When the carburetor is dirty and gummy, the performance of the engine also drops and gradually it fails. Hence, whenever the engine of your two-wheeler cranks or turn over, take it as a warning because it means your carburetor is faulty and needs immediate cleaning or repairing. In such cases, it is wise to clean or repair the carburetor as due to sudden engine failure, your vehicle might get immobilised in the middle of the road when you are driving. To avoid such issues you must have a two wheeler insurance policy in place as most of the insurers provide technical assistance in case your vehicle becomes immobilised due to an engine failure.