Cooling system for a two stroke engine

Claim 1

In combination, a cylinder defining a combustion chamber for a two-stroke internal combustion engine, a piston reciprocable in said cylinder, at least two mutually opposed transfer ports and at least one exhaust port circumferentially spaced from said transfer ports penetrating the wall of said cylinder to communicate with said combustion chamber, and a liquid coolant conducting system in the wall of said cylinder for cooling said cylinder, comprising: a first coolant passage directly below said exhaust port and extending transversely thereof; second coolant passages directly below said transfer ports and extending transversely thereof; means defining a coolant jacket concentrically about said cylinder wall effective to cool said piston throughout the full stroke thereof; upwardly extending laterally spaced coolant passages on opposite sides of said exhaust port connecting said first coolant passage and said coolant jacket; a pair of coolant inlets communicating with said first coolant passage closely adjacent said upwardly extending coolant passages for directing coolant supplied to said system divergently to said upwardly extending coolant passages and said first coolant passage; and at least one coolant outlet from the top of said coolant jacket.