Abstract: A carburetor for feeding separate lean and rich channels of an engine intake duct includes a body having a mixing passage with an air intake side and an engine outlet side. A throttle shutter is rotatable about an axis transverse the mixing passage, and a partition is located within the mixing passage upstream of the throttle shutter. The downstream edge of the partition is adjacent the throttle shutter axis whereby in use of the carburetor the partition defines an extension of the lean and rich channels upstream of the throttle shutter, the partition thus providing substantial isolation between the lean and rich channels for all rotational positions of the throttle shutter. In a preferred embodiment a choke shutter is located upstream of the throttle shutter and is rotatable about a further axis transverse the mixing passage, the upstream edge of the partition being adjacent to the axis of the choke shutter.

Abstract: A carburetor 9 for feeding separate lean and rich channels 12, 13 of an engine intake duct 14 comprises a body 20 having a mixing passage 22 with an air intake side 24 and an engine outlet side 26. A throttle shutter 16 is rotatable about an axis transverse the mixing passage, and a partition 10 is located within the mixing passage upstream of the throttle shutter. The downstream edge of the partition 10 is adjacent the throttle shutter axis 16A whereby in use of the carburetor the partition defines an extension of the lean and rich channels upstream of the throttle shutter, the partition thus providing substantial isolation between the lean and rich channels for all rotational positions of the throttle shutter. In a preferred embodiment a choke shutter 17 is located upstream of the throttle shutter and is rotatable about a further axis 17 A transverse the mixing passage, the upstream edge of the partition being adjacent to the axis of the choke shutter.

Abstract: A carburetor adjustment screw apparatus includes an adjusting screw (2) having a shaft (7) in screw threaded engagement with a carburetor body (4) and a head (8) by which the shaft may be rotated. A generally tubular open-ended housing (10) surrounds the head of the screw and a ring (11) is rotatably mounted in the open end of the housing. Stop means (19/20) limit the angular range of rotation of the ring. A plug (12) is mounted in the ring and engages the screw such that rotation of the plug effects corresponding rotation of the screw. The plug is movable relative to the ring between a first axial position wherein the plug can rotate independently of the ring and a second axial position wherein the plug engages the ring for co-rotation therewith such that the angular range of rotation of the plug is limited to the angular range of rotation of the ring.

Abstract: A fuel adjustment screw apparatus for a diaphragm-type carburetor comprises a screw member (4) having a shaft (4a) and a head (12) by which the shaft may be rotated, with a generally tubular open-ended housing (9) surrounding the head of the screw member. A cap member (10) is mounted in the housing and is movable axially of the screw member between a first position (as seen in FIG. 1) and a second position (FIG. 2). The cap member is held clear of the head of the screw member in the first position so that the screw member can rotate freely, and engages over the head of the screw member in the second position for rotation with the head. The housing has stop means (20) which is engaged by the cap member in the second position for limiting the angle of rotation of the head.

Abstract: A diaphragm-type carburetor has a high speed adjusting needle and a low speed/idle adjusting needle which are independently supplied with fuel from the metering chamber. The path for fuel to the low speed/idle needle has a valve which is controlled by the angular position of the throttle shaft such that when the throttle shutter is closed the valve is open whereas when the throttle shutter is open the valve is closed.

Abstract: A carburetor comprising a main body portion defining a carburetor mixing passage having an air intake side and an engine outlet side, a fuel pump, a throttle shutter mounted within the carburetor mixing passage between the air intake side and the engine outlet side. The carburetor has a metering chamber for supplying fuel from the fuel pump into the carburetor mixing passage via a main discharge port, the main discharge port opens into the carburetor mixing passage on the air intake side of the throttle shutter. A starting fuel supply passage extends from the pressure side of the fuel pump to the carburetor mixing passage. A means is provided for selectively opening and closing the starting fuel supply passage such that when the throttle is in a partially opened position and the starting fuel supply passage is open, the fuel pump causes fuel to be injected through the starting fuel supply passage into the carburetor mixing passage.