Abstract: A two stroke internal combustion engine (1) incorporating an asymmetric exhaust port/transfer port inversion device (2) characterized in that the device includes a hollow flap valve (100) adapted to pivot about a hollow pivot shaft (101) between a closed position and an open position wherein pivoting the device (2) to the open position as the piston (3) begins the compression stroke allows the transfer of air to continue after the leading edge of the piston has closed off the exhaust port (105) thereby advancing the timing of the exhaust port closing and extending the duration of air transfer from the crankcase primary compression chamber (103).

Abstract: A piston cooling system for a pivoted piston (1) for an internal combustion engine, said piston (1) having a piston body (2), a pivot shaft (3) by which the piston body (2) may be pivoted about a pivot axis (4) within a combustion chamber of the internal combustion engine, a first arcuate sealing surface spaced from the pivot axis and transcribing a circumferential path about the pivot axis, and a second arcuate sealing surface radially offset from the first arcuate sealing surface and connected to the first arcuate sealing surface by a floor (5) of the piston body (2), a portion of said floor (5) including a combustion chamber piston crown (6), characterised in that the cooling system includes a coolant path (10) formed in the piston, said coolant path having an entry point at a first end (11) of the pivot shaft (3) and an exit point at a second end (12) of the pivot shaft (3), wherein said coolant path (10) extends from the entry point, through a first portion (13) of the pivot shaft (3), into said piston b

Abstract: A two stroke internal combustion engine (1) incorporating an asymmetric exhaust port/transfer port inversion device (2) characterised in that the device includes a hollow flap valve (100) adapted to pivot about a hollow pivot shaft (101) between a closed position and an open position wherein pivoting the device (2) to the open position as the piston (3) begins the compression stroke allows the transfer of air to continue after the leading edge of the piston has closed off the exhaust port (105) thereby advancing the timing of the exhaust port closing and extending the duration of air transfer from the crankcase primary compression chamber (103).

Abstract: A pivoted piston for an internal combustion engine. The piston has a pivot pin and an arcuate first sealing surface (12) which describes a circumferential path about the pivot pin which forms a removable and replaceable skirt to the piston. The piston also includes a second arcuate sealing surface which also describes a circumferential path about the pivot pin and which is connected to the first arcuate sealing surface (12) by a piston floor (21). The second arcuate sealing surface is composed of at least two arcuate sealing components (24) which are located on a bed (20) with the components (24) being located on the bed (20) so they will have limited transverse movement on the bed (20). The components (24) have mating faces which restrict the path of combustion gases between the mating faces. The piston further includes side seals which are located in grooves (63) in the side of the piston.

Abstract: A pivoted piston for an internal combustion engine. The piston has a pivot pin and an arcuate first sealing surface (12) which describes a circumferential path about the pivot pin which forms a removable and replaceable skirt to the piston. The piston also includes a second arcuate sealing surface which also describes a circumferential path about the pivot pin and which is connected to the first arcuate sealing surface (12) by a piston floor (21). The second arcuate sealing surface is composed of at least two arcuate sealing components (24) which are located on a bed (20) with the components (24) being located on the bed (20) so they will have limited transverse movement on the bed (20). The components (24) have mating faces which restrict the path of combustion gases between the mating faces. The piston further includes side seals which are located in grooves (63) in the side of the piston.

Abstract: A pivoted piston for an internal combustion engine. The piston has a pivot pin and an arcuate first sealing surface (12) which describes a circumferential path about the pivot pin which forms a removable and replaceable skirt to the piston. The piston also includes a second arcuate sealing surface which also describes a circumferential path about the pivot pin and which is connected to the first arcuate sealing surface (12) by a piston floor (21). The second arcuate sealing surface is composed of at least two arcuate sealing components (24) which are located on a bed (20) with the components (24) being located on the bed (20) so they will have limited transverse movement on the bed (20). The components (24) have mating faces which restrict the path of combustion gases between the mating faces. The piston further includes side seals which are located in grooves (63) in the side of the piston.

Abstract: A pivoted piston for an internal combustion engine. The piston has a pivot pin and an arcuate first sealing surface (12) which describes a circumferential path about the pivot pin which forms a removable and replaceable skirt to the piston. The piston also includes a second arcuate sealing surface which also describes a circumferential path about the pivot pin and which is connected to the first arcuate sealing surface (12) by a piston floor (21). The second arcuate sealing surface is composed of at least two arcuate sealing components (24) which are located on a bed (20) with the components (24) being located on the bed (20) so they will have limited transverse movement on the bed (20). The components (24) have mating faces which restrict the path of combustion gases between the mating faces. The piston further includes side seals which are located in grooves (63) in the side of the piston.

Abstract: An internal combustion engine in which the piston (10) rocks about a pivot point (60) with the piston (10) being connected adjacent the end remote from the pivot point (60) to a connecting rod (12) to drive a crankshaft. The piston (10) has a first arcuate sealing surface (41) and a second arcuate sealing surface (42) which is offset radially from the first sealing surface (41) with the first and second sealing surfaces (41, 42) being connected by a floor (44). The first arcuate sealing surface (41) seals against a correspondingly arcuate wall (51) of the combustion chamber (20) and the second arcuate sealing surface (42), which forms one wall of the combustion chamber (20), seals against a wall (52) of a boost chamber (53). The engine can be compression ignition or spark ignition and can be of the two-stroke cycle or four-stroke cycle.