Abstract: A two-stroke internal combustion engine (1) is provided with a muffler device (2). In one example, the engine (1) is intended for a working tool, such as a chain saw or a trimmer. A pipe (3), which either is straight or bent, and having an adapted or tuned length and a closed outer end (4), is arranged in connection to the engine's exhaust port (5) as well as an outlet (6), which leads the exhaust gases to the surrounding air. By this arrangement of the pipe (3) and the outlet (6) the scavenging losses are reduced and thereby the specific fuel consumption is reduced and cleaner exhaust gases are achieved.

Abstract: A two-stroke internal combustion engine (1) is provided with a muffler device (2). In one example, the engine (1) is intended for a working tool, such as a chain saw or a trimmer. A pipe (3), which either is straight or bent, and having an adapted or tuned length and a closed outer end (4), is arranged in connection to the engine's exhaust port (5) as well as an outlet (6), which leads the exhaust gases to the surrounding air. By this arrangement of the pipe (3) and the outlet (6) the scavenging losses are reduced and thereby the specific fuel consumption is reduced and cleaner exhaust gases are achieved.

Abstract: An L-head two stroke engine comprises two pistons mounted for reciprocable movement in first and second cylinders respectively. The cranks of the two pistons are drivably connected such that the pistons are in phase. A fuel/air supply is provided for one cylinder where it is compressed and ignited causing both pistons to return to their respective bottom dead center position. The compression ratio in the one cylinder is less than in the other cylinder so as to aid retention of the air fuel mixture in the one cylinder prior to ignition.

Abstract: A deflector piston two stroke internal combustion engine has a piston (10) reciprocable in a cylinder and sealed thereto by means of piston rings (P2), the cylinder having communicating with it a scavenge part SC2) and an exhaust part (E2). The piston crown has an upper first planar surface lying at right angles to the piston cylinder axis and a lower parallel planar surface, these two surfaces being connected by a deflector edge (D). The upper planar surface co-operates, at or near top-dead-center with a complementary planar surface on the interior (underside as shown) of the cylinder head with which it has a minimum clearance C2. The approach of these surfaces as top-dead-center is approached generates a "squish" that is a jet of fuel/air mixture in the direction of arrow (S2) towards the spark plug which improves combustion.

Abstract: In a crankcase scavenged two-stroke internal combustion engine, a duct and at least one further passage extends between the crankcase chamber and the combustion chamber. There is a fuel/air mixture port leading into the duct and a pure air port leading into the duct or the crankcase chamber. The passage exits into the combustion chamber between the exit into that chamber from the duct and an exhaust port leading out of the combustion chamber. In operation fuel enters the combustion chamber in the air of the fuel/air stream entering the duct and air is additionally pushed into the combustion chamber by the downward movement of the piston through the passage and the duct. The fuel is separated from the exhaust port by a layer of air leading to better fuel consumption and higher oxidation combustion products.