Abstract: A camshaft and methods of installing a camshaft, the camshaft having at least one detachable bearing journal to enable varied camshaft designs to be assembled into an engine.

Abstract: The invention relates to methods and means of regulating the speed of a two-stroke combustion engine. An arrangement for alternating an ignition timing relative to a top dead center position is provided. For a given engine speed, the ignition timing may be step-wise adjustable. One or more steps may be used while alternating between two ignition timings. The ignition timing may be adjusted when the engine speed increases above a threshold engine speed.

Abstract: The invention relates to a camshaft for a small internal combustion engine used in for example cars or motorbikes, it is characterized by being divided into two or more components, preferably it is the camshaft bearing journals (3) on the camshaft that are separate components. With a camshaft in one piece the camshaft lobes (4) cannot have a larger radius than the camshaft bearing journals (3) if the camshaft is to be inserted through the camshaft support bearings (2) in the engine. The bearing journals (3) will then limit the design and height of the camshaft lobes (4). By designing the camshaft divided in separate components to be assembled at the same time or after the camshaft has been inserted into the engine, it is possible to insert the camshaft radially displaced through the camshaft support bearings (2). This makes it possible to design the camshaft lobes (4) larger than what would otherwise be possible for given dimension of the support bearings (2).

Abstract: The invention relates to methods and means of regulating the speed of a two-stroke combustion engine. An arrangement for alternating an ignition timing relative to a top dead center position is provided. For a given engine speed, the ignition timing may be step-wise adjustable. One or more steps may be used while alternating between two ignition timings. The ignition timing may be adjusted when the engine speed increases above a threshold engine speed.

Abstract: Method for treating a crank pin of a crank shaft. In the method hardness of the crank pin surface is measured and when the hardness is over a predetermined limit value, depth of the hard spot is measured. Heat treatment parameters are determined at least on the basis of the depth measurement and the hard spot is heat treated. During the heat treatment the hard spot is heated by an induction heating device.

Abstract: Method for adjusting the air-fuel ratio of an internal combustion engine, in a fuel supply section thereof, such as a carburettor or a fuel-injection system, the fuel supply section having a control unit for adjusting the air-fuel ratio of the engine, and the engine having an engine speed and an engine throttle ranging from zero throttle to full throttle. The method including: a) measuring the engine speed of the engine; b) comparing the engine speed to a first engine speed value; c) adjusting the air fuel ratio if the engine speed is lower than the first engine speed value; and d) repeating a) to c) until the engine speed is either greater than or equal to the first engine speed value.

Abstract: Method for treating a crank pin of a crank shaft. In the method hardness of the crank pin surface is measured and when the hardness is over a predetermined limit value, depth of the hard spot is measured. Heat treatment parameters are determined at least on the basis of the depth measurement and the hard spot is heat treated. During the heat treatment the hard spot is heated by an induction heating device.

Abstract: A crankcase scavenged two-stroke engine (1) comprises a cylinder (15) including scavenging ports (31, 31?) and at least one exhaust port, a piston (13), a connecting rod (17), a crankshaft (18) and a generally sealed crankcase (16). The crankcase inducts a fuel/air mixture and is connected to the scavenging ports (31, 31?) by means of transfer ducts (3, 3?) which, as the piston (13) is travelling from a lower position towards a higher position, are inducting pure air let in from connecting ports (8, 8?) near the scavenging ports (31, 31?) in the cylinder (15). The transfer duct (3, 3?) volume is less than 20% of a volume swept by the piston (13) during an entire revolution of the crankshaft (18). Recesses (10, 10?) are formed in an outer periphery of the piston (13), said recesses (10, 10?) co-operating with the connecting ports (8, 8?) in the cylinder wall for controlling the filling of the transfer ducts (3, 3?) with air.

Abstract: A crankcase scavenged two-stroke engine (1) comprises a cylinder (15) including scavenging ports (31, 31?) and at least one exhaust port, a piston (13), a connecting rod (17), a crankshaft (18) and a generally sealed crankcase (16). The crankcase inducts a fuel/air mixture and is connected to the scavenging ports (31, 31?) by means of transfer ducts (3, 3?) which, as the piston (13) is travelling from a lower position towards a higher position, are inducting pure air let in from connecting ports (8, 8?) near the scavenging ports (31, 31?) in the cylinder (15). The transfer duct (3, 3?) volume is less than 20% of a volume swept by the piston (13) during an entire revolution of the crankshaft (18). Recesses (10, 10?) are formed in an outer periphery of the piston (13), said recesses (10, 10?) co-operating with the connecting ports (8, 8?) in the cylinder wall for controlling the filling of the transfer ducts (3, 3?) with air.

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.