with a piston 38 reciprocably movable in the respective cylinder 27 the piston controls the opening of at least one exhaust port 39 and intake port 40 the latter being connected by a transfer passage 42 to the crankcase chamber 34 in place of the reed type intake check valves commonly used to admit air to the crankcase chambers of such two cycle engines each chamber 34 has an air inlet fitting 43 that mounts a poppet valve housing 44 the housing 44 defines an air passage 46 in which is an electric solenoid 47 connected with poppet valve 48 the valve has a head 50 that normally closes an inlet opening 51 in an end wall 52 of the housing 44 to block the flow of air between the passage 46 and an adjoining inlet port 54 defined by the fitting 43 actuation of the solenoid to open the valve 48 is controlled by a control unit 55 such as an engine computer which connects with both the solenoid and the fuel injection system to control the timing of valve opening and the admission of air as a function of the fuel delivery and the related engine load in operation as the engine fuel control which can be a separate unit or incorporated in the control unit 55 varies the fuel delivery in response to the operator 39 s demands for engine performance i e the selected engine load the control unit varies the opening time of the crankcase poppet valve to provide the proper amount of retained charge in the crankcase for delivery to the cylinder pumping work is reduced at part load as explained previously because the intake air is not throttled but is controlled instead by the timing of valve opening.