A two cycle internal combustion spark ignition engine comprising in combination:
- (a) minimum of two side by side spaced apart axially parallel cylinders,
- (b) a hollow guideway parallel to and positioned between said cylinders,
- (c) one variable volume combustion chamber,
- (d) air intake porting located in each cylinder wall at a first end of said combustion chamber, having an upstream end and a downstream end,
- (e) exhaust porting located in each cylinder wall at a second end of said combustion chamber,
- (f) means for delivering fuel into said cylinders approximately midway of the length of said combustion chamber, and when said combustion chamber is at its approximate minimum volume, said means including a precombustion chamber common to and in communication with said combustion chamber of each of said cylinders, said precombustion chamber being positioned outside of the plane of the axes of said cylinders,
- (g) at least one spark plug for igniting a mixture of fuel and air in said combustion chamber,
- (h) one cylindrical single headed pressure sealing valveless air intake controlling piston coaxial with and slidably mounted within each of said cylinders, said piston having its head end facing the combustion chamber and its connector end facing a first non-combustion end of said cylinder, said piston opening and closing said downstream end of said air intake porting as it slides past said air intake porting,
- (i) a rigid non-pivotal piston bridging means spanning from piston axis to piston axis of said air intake controlling pistons,
- (j) dual rigid and operationally non-pivotal piston connector means extending from said piston bridging means, said piston connector means being adapted to link said piston bridging means with said air intake controlling pistons at said pistons' connector ends,
- (k) bridge guide means extending from said piston bridging means into said hollow guideway for opening and closing said upstream end of said air intake porting as it slides past said air intake porting, said bridge guide means terminating in a connecting rod pivot means,
- (l) one cylindrical single headed pressure sealing valveless exhaust controlling piston coaxial with and slidably mounted within each of said cylinders, said piston having its head end facing said combustion chamber and its connector end facing a second non-combustion end of said cylinders, said piston being adapted to open and close said exhaust porting as it slides past said exhaust porting,
- (m) a second rigid non-pivotal piston bridging means spanning from piston axis to piston axis of said exhaust controlling pistons,
- (n) second dual rigid and operationally non-pivotal connector means extending from said second piston bridging means, said second piston connector means being adapted to link said second piston bridging means with said exhaust controlling pistons at said pistons' connector ends,
- (o) a single crankshaft located between said parallel axes of said cylinders and between the two piston bridging means, the axis of said crankshaft being at right angles to the plane of said cylinders' parallel axis,
- (p) at least two connecting rods between said two piston bridging means, one of said connecting rods being connected to pivot means of said bridge guide means and to said crankshaft and a second connecting rod connected to said second piston bridging means and to said crankshaft,
- (q) said connections to said crankshaft being made to angularly spaced cranks carried by said single crankshaft, said angular spacing of said cranks being such that as the crankshaft rotates through 360.degree., said two piston bridging means and their respectively connected pistons are forced to move in opposite directions, the two air intake controlling pistons being reciprocated in unison and the two exhaust controlling pistons likewise being reciprocated in unison and wherein said air intake controlling pistons are forced to lag behind said exhaust controlling pistons in such a manner that said exhaust porting is forced to open prior to the opening of said air intake porting and said exhaust porting is forced to close prior to the closing of said air intake porting.