Carburetor explained


What is a Carburetor?

Fuel Systems Explained - Carburator

In a nutshell a carburetor is a device that helps in mixing air and fuel in the proper ratio in order to deliver the right mixture to the combustion chamber. Air to fuel ratio varies between 12:1 and 14.7:1. The 12:1 mixture is called a rich mixture which is necessary for starting and acceleration. The lean mixture is required for cruising speeds. Based on the position of the throttle valve (inside the carburetor), lean or rich mixture is sent to the combustion chamber. There, the charge (A/F mixture) is ignited by a spark plug and combustion commences.

What are the advantages?

As motorcycles started to be produced at an unprecedented rate, the demand for carburetors was at an all-time high. The principle of operation was fairly simple and it was very cost effective to produce. The use of electronics of bikes was slightly complicated and not very trustworthy. A fuel-injected bike those days also refused to deliver the zest one had come to experience on a carbureted bike. The fuel-injector required the use of sophisticated sensors and pressure pumps which usually shot up cost of production. Also, it was cheaper to adjust the carburetor than to change fuel maps on the ECU (for injectors). To say that the fuel-injected bikes develop more horsepower is also not true as some of the powerful bikes in history were carbureted.

What are the limitations?

The age of the fuel-injector began at a time when people started to realise that a carburetor is not that great for planet earth. Carburetors or Carbs are not very precise and depend on atmospheric pressure. Too lean or too rich mixture entering the combustion chamber will result in poor combustion which in turn churns out Carbon monoxide and oxides of Nitrogen into the atmosphere. Also when the bike is not running, fuel stored in the carburetor bowl tends to evaporate which results in unburnt hydrocarbons being emitted into the atmosphere.

Scope for the future

So, is the Carburetor becoming irrelevant as every minute passes? Certainly not, especially in a volume focussed market like India where majority of bikes are sold only because they are affordable and cheap to run. Manufacturers in India just cannot accommodate for the high cost of the fuel-injectors. Hopefully, in the future, more stringent emission norms will force manufacturers to switch to an injector. Major manufacturers like Hero Motocorp, Yamaha and Bajaj have started to introduce fuel-injected bikes recently, which is a good sign. Even the iconic Royal Enfield has joined the fray by using fuel-injection on the Continental GT. However, in the short term, new bikes, especially in the commuter segment will continue to be equipped with carburetors.