Abstract: An intake system for a single or multi-cylinder motorcycle engine comprising one or more cylinders each provided with at least one fuel injector (15), said engine (3) comprising at least one air intake duct (8) and at least one duct (10) for delivering the air towards intake conduits (4) for said cylinders. These latter are not provided with a valving member, said valving member (20) being instead provided in the intake duct (8) of the air box (1), the fuel injectors (15) being disposed above the intake conduits (4) of the corresponding cylinders and being provided downstream of the valving member (20) of the intake duct (8) for the air box (1).