Carburettor

A fixed choke carburettor arranged to supply fuel to a two stroke engine, the carburettor comprising an inlet duct, a throttle valve arranged to throttle a flow of air through the inlet duct, the inlet duct being divided over at least part of its length into a rich passage and a lean passage which are arranged to communicate with a rich volume and a lean volume respectively of the engine, the carburettor and throttle valve being adapted to supply, under high load operation, substantially all fuel into the rich passage, and to supply fuel into both the rich and lean passages under low load operation, and a venturi section extending in a radial direction of the inlet duct for less than the full circumference of the duct.

A carburettor for a two stroke engine including a flow duct comprising rich and lean flow passages separated by a partition, at least one fuel jet communicating with the rich passage, the partition including an aperture towards which the fuel jet is directed, and a substantially planar butterfly valve being received in the aperture so as to be pivotable between a first position, in which the flow duct is substantially closed and the aperture is substantially open, and a second position, in which the flow duct is substantially open and the aperture is substantially closed, the throttle valve being disposed on a spindle for pivotal movement thereon, the spindle and throttle valve being arranged such that in the second position the spindle is contained within the rich passage.

A fixed choke carburettor arranged to supply fuel to a two stroke engine, the carburettor comprising an inlet duct, a throttle valve arranged to throttle a flow of air through the inlet duct, the inlet duct being divided over at least part of its length into a rich passage and a lean passage which are arranged to communicate with a rich volume and a lean volume respectively of the engine, the carburettor and throttle valve being adapted to supply, under high load operation, substantially all fuel into the rich passage, and to supply fuel into both the rich and lean passages under low load operation, the throttle valve being disposed on a spindle for pivotal movement thereon, the spindle and throttle valve being arranged such that under high load operation at substantially full throttle, the spindle is wholly contained within the predominantly rich passage.