An exhaust valve assembly for a two-stroke internal combustion engine, the engine having a cylinder block defining a cylinder and a piston movably disposed within the cylinder, the cylinder defining an exhaust port for discharging exhaust fluids from the cylinder, the exhaust valve assembly comprising: a shaft configured to be rotatably supported by the cylinder block of the engine, the shaft extending along a central axis; a valve connected to the shaft and configured to cyclically obstruct the exhaust port of the cylinder, the valve having an inner surface and an outer surface, the valve being configured such that: the inner surface of the valve has a cross-sectional profile taken along a plane normal to the central axis; and the outer surface of the valve defines an axial curvature of the valve, the axial curvature being configured to have a radius that is greater than a radius of the cylinder, the axial curvature of the valve defining an arcuate axis, and the cross-sectional profile of the inner surface of the valve has a generally triangular shape defined by two sides of the inner surface converging at an apex; the exhaust valve assembly being characterized in that: the arcuate axis is configured to be further from the outer surface of the valve than a cylinder axis defined by the cylinder in a plane normal to the cylinder axis and containing the central axis when the outer surface of the valve faces the cylinder. a shaft configured to be rotatably supported by the cylinder block of the engine, the shaft extending along a central axis; a valve connected to the shaft and configured to cyclically obstruct the exhaust port of the cylinder, the valve having an inner surface and an outer surface, the valve being configured such that: the inner surface of the valve has a cross-sectional profile taken along a plane normal to the central axis; and the outer surface of the valve defines an axial curvature of the valve, the axial curvature being configured to have a radius that is greater than a radius of the cylinder, the axial curvature of the valve defining an arcuate axis, and the cross-sectional profile of the inner surface of the valve has a generally triangular shape defined by two sides of the inner surface converging at an apex; the exhaust valve assembly being characterized in that: the arcuate axis is configured to be further from the outer surface of the valve than a cylinder axis defined by the cylinder in a plane normal to the cylinder axis and containing the central axis when the outer surface of the valve faces the cylinder. the inner surface of the valve has a cross-sectional profile taken along a plane normal to the central axis; and the outer surface of the valve defines an axial curvature of the valve, the axial curvature being configured to have a radius that is greater than a radius of the cylinder, the axial curvature of the valve defining an arcuate axis, and the cross-sectional profile of the inner surface of the valve has a generally triangular shape defined by two sides of the inner surface converging at an apex; the exhaust valve assembly being characterized in that: the arcuate axis is configured to be further from the outer surface of the valve than a cylinder axis defined by the cylinder in a plane normal to the cylinder axis and containing the central axis when the outer surface of the valve faces the cylinder.