Carburettor and Fuel Injection What are the Key Differences

Bikers are often heavily invested in the functioning and make of their vehicle. Thus, there have been massive ongoing debates regarding the riding experience in motorbikes powered by carburettor and fuel injection engines.

Now, how is carburetion different from fuel injection? Does the fuel delivery technique impact engine performance? Will fuel injection systems completely wipe out carburettors in the future? Let’s have a detailed look at them both.

Carburetion

The first carburettor was developed by Karl Benz.

Until recent times, the carburettor was the most common and basic fuel delivery system in two-wheelers. The setup of a carburettor is quite simplistic and mechanical and does not make any use of sensors and or electronics. For example, the Discover is a 100 cc bike from Bajaj and comes equipped with a carburettor.

How it Works

The inlet pipe of a carburettor feeds an air-fuel mixture into the cylinder while an air filter is attached to the outlet. In the venturi, the tube tapers to restrict air passage, which increases the velocity with which the air moves through it.

Following Bernoulli's principle, the increased velocity results in a low-pressure condition, which uses suction to draw out fuel from a jet near the venturi. The air-fuel mixture gets supplied to the cylinder where the combustion takes place.

A valve, called the throttle valve, is present at the end of the tube and is connected to the cylinder. It controls the air sucked into the carburettors. The throttle valve is connected to the accelerator of your bike. Thus, revving up the throttle increases the airflow, thereby delivering more fuel, while rolling it back does vice versa.

Pros

  • Since a carburettor has a purely simplistic and mechanical build, it does not cost a lot.
  • Maintenance and replacement of carburettors is not an expensive affair.
  • Tuning and setting of carburettors are possible while on the go. Plus, it can be quickly serviced.
  • It can be opened as an individual unit without disturbing the engine.

Cons

  • The diaphragm of a carburettor is delicate and can tear easily. Also, the carburettor design is obsolete.
  • The open nature of the carburettor, it loses its efficiency due to pumping losses caused by evaporation.
  • While carburettors are precise, they are not accurate. A carburettor’s accuracy may be hampered by air or fuel temperature changes or atmospheric pressure changes.
  • Low temperatures may make it difficult to start a bike that is powered by a carburettor.

Fuel Injection

Fuel injectors are considered to be far more superior to carburettors as they make use of sensors and electronics that automate most of the tasks.

How it Works

In this fuel delivery system, a fuel injection nozzle is fed directly inside the combustion chamber, while the air intake is measured using an air sensor. Upon entering the pressure pump, the fuel and air are subjected to pressure and get atomised into a homogenous mist, which allows for clean and efficient combustion.

The supply of the fuel-air mist is controlled by an ECU, which makes use of dynamic, complex calculations to deliver the best air-fuel mixture based on factors like load, engine speed, engine temperature, throttle position, etc.

Pros

  • Optimum fuel delivery with a consistent air to fuel ratio, which may be modified on a case-to-case basis as computed by the ECU.
  • Increased fuel efficiency and higher power output.
  • Greater throttle sensitivity, which offers a quicker response to acceleration.

Cons

  • Servicing and maintenance of a fuel injection system are expensive.
  • If the ECU fails, the entire fuel delivery system will fail, rendering your bike useless.
  • The replacement of fuel injection systems is expensive.

Which One Takes the Cake

Even though the advantages of a fuel injection system greatly outweigh the humble carburettor, the costs involved in repairing, maintaining, and replacing fuel injection can be quite a deterrent. Using poor quality fuel can damage a fuel injection system, which is a common cause for concern lately.

Carburettors, on the other hand, are reliable, inexpensive and easier to maintain.
A good practice could be opting for a carburettor for small capacity bikes, that is, less than 250 cc.

Conversely, if you are availing a 2-wheeler loan to purchase your dream bike then throw in a little extra money and go all in for a fuel injection system.