Abstract: A side draft carburetor for motorcycles. The carburetor has a body with a horizontal airflow passageway, the airflow through which is controlled by a butterfly valve near the exit side of the carburetor. An upper cylinder is vertically positioned over the airflow passageway and has a large inside diameter portion and a smaller inside diameter portion. A piston member is vertically moveable in the upper cylinder and has an upper piston portion which is fitted in an airtight manner but freely moveable in the upper cylinder and a lower piston member is closely fitted in the lower cylinder. An airflow passageway to the outside of the carburetor body is provided at the base of the upper cylinder. The piston member is closed at the bottom except for an airflow passageway. A tapered needle is held by the piston member and extends downwardly into a jet assembly held in a jet holding member.