A valve drive comprising a camshaft with base shaft, a lobe pack mounted on the base shaft and comprising three cam lobes. Two actuator bodies are associated with two actuator pins each connected to a valve of a cylinder of the engine. The lobe pack is axially displaceable along the base shaft so as to for each actuator body change cam lobe aligned therewith. A middle cam lobe has a shape leaving an actuator body aligned therewith uninfluenced thereby. In a first position of the lobe pack a first of the actuator bodies is aligned with and hit and moved by a first cam lobe and the other, second actuator body is aligned with the middle cam lobe, and in a second position the second actuator body is aligned with and hit and moved by a third cam lobe and the first actuator body is aligned with the middle cam lobe.

A compact and efficient Z-twin internal combustion engine is described herein. The Z-twin internal combustion engine comprises horizontally opposed cylinder arrangement that allows for vibration cancellation. The Z-twin engine comprises a central shared cam that drives angled side valves of both the opposing cylinders, thereby greatly reducing moving parts and thus provides a significantly more efficient angled valve approach.

In a cylinder lubrication system for a two-stroke engine, a plurality of lubricating oil supply openings (78) open out in the inner circumferential surface of the cylinder (42) at a point lower than a top ring (22b) of a piston (22) located at a bottom dead center. The lubricating oil supply openings are configured to provide a larger amount of lubricating oil in the thrust side and anti-thrust side of the cylinder than in a remaining part of the cylinder. Thereby, the consumption of lubricating oil and the emission of undesired substances can be minimized while providing an optimum lubrication of the sliding part between the piston and the cylinder.

In a cylinder lubrication system for a two-stroke engine, a plurality of lubricating oil supply openings (78) open out in the inner circumferential surface of the cylinder (42) at a point lower than a top ring (22b) of a piston (22) located at a bottom dead center. The lubricating oil supply openings are configured to provide a larger amount of lubricating oil in the thrust side and anti-thrust side of the cylinder than in a remaining part of the cylinder. Thereby, the consumption of lubricating oil and the emission of undesired substances can be minimized while providing an optimum lubrication of the sliding part between the piston and the cylinder.