Four cycle engine carburetors

A dual passage gaseous fuel carburetor having:

• a body (102, 2034b);
• a sliding drum (2079a) in the body (102, 2034b);
• a first passage (2581) for air-fuel mixture;
• a second passage (2194) for air only;
• a cut out (404) in the sliding drum (2079a) is axially at a distance away from the lower edge (2080) and movable axially as the sliding drum (2079a) is lifted axially;
• flow area (2581a) under the lower edge (2080) and the flow area (2194a) for the first fraction increase simultaneously from partially open to fully open flow areas as the sliding drum (2079a) is lifted axially;
• a variable venturi (2581a), in which the sliding drum is movable up and down to change the area of the variable venturi and regulate the mixing of air and fuel in the first passage (2581), and to simultaneously regulate the air flow in the second passage (2194);
• a fuel regulating needle (407) at the bottom of the sliding drum (2079a);
• at least one pressure regulating chamber (105) within the body;
• a metering (116) chamber within the body;
• and
• at least one pressure regulator, in which each of the pressure regulators comprise:
• an LPG inlet;
• at least one diaphragm;
• at least one needle valve (111);
• at least one arm;
• at least one pressure regulator cover with at least one vent hole in the at least one pressure regulator cover;
• and
• at least one pressure spring.