Two-stroke, water-cooled internal combustion engine having the cylinder liners removable from the cylinder block

In a two-stroke internal combustion engine of the compression crankcase type:

• an engine block having at least one cavity which defines a seating with a substantially annular bottom wall and with a discrete number of spaced apart lateral resting surfaces formed in correspondence with the top surface of the engine block;
• an engine head releasably attached to the top surface of the engine block, the annular bottom wall receiving in sealtight manner the lower edge of an inserted cylinder liner, the exterior surface of said liner forming with the engine block a cooling jacket and the top edge of the liner being laterally received on said resting surfaces and confined at its top by a surface which is substantially coplanar with the top surface of the engine block so as to receive in a sealtight manner the engine head, the liner having transfer ducts formed therethrough in portions of the liner which project laterally outward of the remainder of the liner, said resting surfaces of the engine block receiving the top edge of the liner in correspondence with sectors thereof which are spaced from the areas from which the transfer ducts project, so that the liner can be slipped out of the engine block, the liner having at least one exhuast port formed therethrough and the block having an exhaust duct disposed at the location of the exhaust port, means for providing a tight seal between said exhaust port and said exhaust duct, said means including a fitting in the form of a sleeve and means for clamping the sleeve to the liner and to corresponding resting surfaces on the block.