Carburetor

A carburetor is a mechanical device that mixes air and fuel in the correct ratio for combustion. It works using the Venturi effect: as air is drawn through a narrowing passage, its velocity increases and pressure drops, which pulls fuel from a reservoir (the float bowl) and atomizes it into the airstream. Carburetors were the standard fuel delivery system on motorcycles until fuel injection replaced them starting in the early 2000s.

Carburetors have multiple circuits that handle different throttle positions: an idle circuit for no-throttle operation, a needle/slide circuit for mid-range, and a main jet for wide-open throttle. Tuning a carburetor involves selecting the correct jet sizes and adjusting needle positions — a process called "jetting" — to achieve optimal air-fuel mixtures across all throttle ranges.

For riders considering older, carbureted motorcycles, be prepared for some additional maintenance. Carburetors can become clogged if a bike sits unused with fuel in the system (varnish from old fuel blocks tiny passages). They may also need re-jetting for different altitudes or aftermarket exhaust systems. On the positive side, carburetors are entirely mechanical, making them repairable without specialized electronics or dealership software.

Despite being replaced by fuel injection on modern bikes, carburetors remain beloved by mechanically-minded riders for their tuneability and analog feel. Performance modifications are straightforward: install aftermarket exhaust and air filter, then re-jet with larger main jets to match the increased airflow. You can physically see and touch every component, making troubleshooting intuitive. Carburetors also work without electricity, which is why some adventure riders prefer older carbureted bikes for remote travel where electronic failures could strand you.