Abstract: A carburettor for an internal combustion engine has an air passageway in which air flow is controlled by a poppet valve in which fuel is fed from a tapered needle controlled valve readily variable for different fuels including CNG, LPG, Methanol and petrol. A movable assembly comprises the poppet valve connected to a movable wall, the latter separating a first and second pressure chamber and a low pressure control valve is manually programmable to take up a position relative to the movable assembly preferably the movable wall to control pressure in the first pressure chamber against a balancing pressure in the second pressure chamber and a biasing means to control the position of the poppet valve and the fuel valve and hence the power of an internal combustion engine on which the carburettor is fixed in accordance with selected positions of a manual control.