An engine includes: a carburetor configured to supply an air-fuel mixture of fuel and air; a crank case defining a crank chamber; a cylinder block which includes: a cylinder bore in which a reciprocable piston is disposed; and an intake port which supplies the air-fuel mixture supplied from the carburetor to the crank chamber; a control valve configured to open and close the intake port; and a controller configured to control the control valve. The controller controls the number of times that the control valve closes the intake port with respect to the number of times that the piston moves up to thereby reduce pressure of the crank chamber.