Exhaust valve assembly for a two-stroke internal combustion engine

A two-stroke internal combustion engine comprising:

• a crankcase;
• a crankshaft disposed at least in part in the crankcase;
• a cylinder block connected to the crankcase;
• a cylinder defined in the cylinder block and having a cylinder axis, the cylinder defining at least one exhaust port for discharging exhaust fluid from the cylinder;
• a piston movably disposed within the cylinder and being operatively connected to the crankshaft, the piston being movable along the cylinder axis in a reciprocating motion including an upstroke and a downstroke;
• an exhaust valve assembly operatively connected to and rotatable with the crankshaft, the exhaust valve assembly comprising:
• a shaft rotatably supported by the cylinder block and extending along a central axis, the shaft being discontinuous such that the shaft comprises a first portion and a second portion spaced apart from the first portion in a direction of the central axis;
• a valve connected to the shaft and configured to cyclically obstruct the exhaust port, the valve having two ends opposite one another in the direction of the central axis and defining a length of the valve therebetween, the valve being disposed between and separating the first portion and the second portion of the shaft such that the shaft does not extend along the length of the valve in the direction of the central axis, the valve being operable to:
• move clear of the exhaust port before the piston uncovers the exhaust port during the downstroke of the piston, and
• at least partially close the exhaust port before the piston fully covers the exhaust port during the upstroke of the piston.