Abstract: A crankshaft (1) for a crankcase scavenged two stroke piston engine (2) is disclosed. The crankshaft (1) is configured to rotate around a rotation axis (ax) during operation. The crankshaft (1) comprises a crankpin (3) configured to move in a crank plane (cp) during operation, and a first and a second counterweight (5, 7) arranged on either side (S1, S2) of the crank plane (cp). The first counterweight (5) has a first outer radius (r1) measured from the rotation axis (ax) and the second counterweight (7) has a second outer radius (r2) measured from the rotation axis (ax). The first outer radius (r1) is smaller than the second outer radius (r2). The present disclosure further relates to a power unit (10), a crankcase scavenged two stroke piston engine (2), and a hand-held power tool (20).

Abstract: A crankshaft (1) for a crankcase scavenged two stroke piston engine (2) is disclosed. The crankshaft (1) is configured to rotate around a rotation axis (ax) during operation. The crankshaft (1) comprises a crankpin (3) configured to move in a crank plane (cp) during operation, and a first and a second counterweight (5, 7) arranged on either side (S1, S2) of the crank plane (cp). The first counterweight (5) has a first outer radius (r1) measured from the rotation axis (ax) and the second counterweight (7) has a second outer radius (r2) measured from the rotation axis (ax). The first outer radius (r1) is smaller than the second outer radius (r2). The present disclosure further relates to a power unit (10), a crankcase scavenged two stroke piston engine (2), and a hand-held power tool (20).

Abstract: A crankcase scavenged two-stroke internal combustion engine (1) having an additional air supply (2) arranged to its transfer ducts (3), connecting a crankcase volume (4) and a transfer port (5). There is at least one recess (6, 24) in a piston (7) arranged below a piston ring (10, 11), and further there is a flow channel (12; 13; 14) arranged in the piston or in a cylinder wall (29) of the engine cylinder (9), and the recess is arranged to register with the transfer port and the flow channel for certain first piston positions, i.e. to create a communication between the transfer port/s and the crankcase volume.

Abstract: A crankcase scavenged two-stroke internal combustion engine (1) having an additional air supply (2) arranged to its transfer ducts (3), connecting a crankcase volume (4) and a transfer port (5). There is at least one recess (6, 24) in a piston (7) arranged below a piston ring (10, 11), and further there is a flow channel (12; 13; 14) arranged in the piston or in a cylinder wall (29) of the engine cylinder (9), and the recess is arranged to register with the transfer port and the flow channel for certain first piston positions, i.e. to create a communication between the transfer port/s and the crankcase volume.