A method of operation of exhaust valves of an adjustable exhaust port 2-stroke motorcycle engine with a two stage exhaust valve system includes: providing a control rod mechanically coupled to a governor, so that the governor causes a rotation of the control rod. A first stage exhaust valve, a second stage left exhaust valve, and a second stage right exhaust valve are also controllably linked to the control rod; and operating the second stage left exhaust valve and the second stage right exhaust valve by opening at least one of the second stage left exhaust valve and the second stage right exhaust valve before the first stage exhaust valve is completely open in an overlap operation. Related methods and structures for overlap, and/or stagger, and/or limiter operation of exhaust valves of an adjustable exhaust port 2-stroke motorcycle engine are also described.

A method of operation of exhaust valves of an adjustable exhaust port 2-stroke motorcycle engine with a two stage exhaust valve system includes: providing a control rod mechanically coupled to a governor, so that the governor causes a rotation of the control rod. A first stage exhaust valve, a second stage left exhaust valve, and a second stage right exhaust valve are also controllably linked to the control rod; and operating the second stage left exhaust valve and the second stage right exhaust valve by opening at least one of the second stage left exhaust valve and the second stage right exhaust valve before the first stage exhaust valve is completely open in an overlap operation. Related methods and structures for overlap, and/or stagger, and/or limiter operation of exhaust valves of an adjustable exhaust port 2-stroke motorcycle engine are also described.

An adjustable exhaust port 2-stroke motorcycle engine with a center adjustable exhaust valve or a split center adjustable exhaust valves includes a closing fork. The closing fork or closing arm base portion is screwed or bolted to a control rod shaft. At least one spring is disposed between a surface of an engine cylinder and the at least one transverse post of an exhaust valve. A first end of the at least one spring is in contact with the surface of an engine cylinder or a surface fixed mounted to the surface of the engine cylinder, and a second end of the spring is in contact with or linked to the at least one transverse post. The center adjustable exhaust valve or either or both of a split center adjustable exhaust valves is spring biased to an open position by the at least one spring at all times.

An adjustable exhaust port 2-stroke motorcycle engine with a center adjustable exhaust valve or a split center adjustable exhaust valves includes a closing fork. The closing fork or closing arm base portion is screwed or bolted to a control rod shaft. At least one spring is disposed between a surface of an engine cylinder and the at least one transverse post of an exhaust valve. A first end of the at least one spring is in contact with the surface of an engine cylinder or a surface fixed mounted to the surface of the engine cylinder, and a second end of the spring is in contact with or linked to the at least one transverse post. The center adjustable exhaust valve or either or both of a split center adjustable exhaust valves is spring biased to an open position by the at least one spring at all times.

Provided is a reverse osmosis treatment system capable of simultaneously and efficiently recovering energy generated both at brine and permeate sides. The system comprises a branched portion configured to divide second to-be-treated water into third and fourth to-be-treated water; a high-pressure pump configured to pressurize the third to-be-treated water thereby to feed fifth to-be-treated water having a higher pressure than the to-be-treated water before divided; a displacement type of first energy recovery device configured to exchange pressures between the fourth to-be-treated water and brine thus separated by a reverse osmosis treatment device, thereby to produce sixth to-be-treated water having a higher pressure than the fourth one; and a second energy recovery device configured to raise a pressure of the third to-be-treated water located at a downstream side of the branched portion with a pressure of first permeate thus separated by the reverse osmosis treatment device.

Provided is a reverse osmosis treatment system capable of simultaneously and efficiently recovering energy generated both at brine and permeate sides. The system comprises a branched portion configured to divide second to-be-treated water into third and fourth to-be-treated water; a high-pressure pump configured to pressurize the third to-be-treated water thereby to feed fifth to-be-treated water having a higher pressure than the to-be-treated water before divided; a displacement type of first energy recovery device configured to exchange pressures between the fourth to-be-treated water and brine thus separated by a reverse osmosis treatment device, thereby to produce sixth to-be-treated water having a higher pressure than the fourth one; and a second energy recovery device configured to raise a pressure of the third to-be-treated water located at a downstream side of the branched portion with a pressure of first permeate thus separated by the reverse osmosis treatment device.

Provided is a reverse osmosis treatment system capable of simultaneously and efficiently recovering energy generated both at brine and permeate sides. The system comprises a branched portion configured to divide second to-be-treated water into third and fourth to-be-treated water; a high-pressure pump configured to pressurize the third to-be-treated water thereby to feed fifth to-be-treated water having a higher pressure than the to-be-treated water before divided; a displacement type of first energy recovery device configured to exchange pressures between the fourth to-be-treated water and brine thus separated by a reverse osmosis treatment device, thereby to produce sixth to-be-treated water having a higher pressure than the fourth one; and a second energy recovery device configured to raise a pressure of the third to-be-treated water located at a downstream side of the branched portion with a pressure of first permeate thus separated by the reverse osmosis treatment device.

In an engine valve, a first sliding area formed at a valve head side in an outer face of a valve stem, and sliding along a stem guide, a second sliding area formed at an opposite side from the valve head side, and sliding along the stem guide, and a first small diameter area formed between the first sliding area and the second sliding area are formed. Further, in the engine valve, a length, in an axial direction of the valve stem, of the first sliding area abutting on the stem guide at a position where the engine valve is fully opened is longer as compared with a length, in the axial direction of the valve stem, of the second sliding area abutting on the stem guide at a position where the engine valve is fully closed.

In an engine valve, a first sliding area formed at a valve head side in an outer face of a valve stem, and sliding along a stem guide, a second sliding area formed at an opposite side from the valve head side, and sliding along the stem guide, and a first small diameter area formed between the first sliding area and the second sliding area are formed. Further, in the engine valve, a length, in an axial direction of the valve stem, of the first sliding area abutting on the stem guide at a position where the engine valve is fully opened is longer as compared with a length, in the axial direction of the valve stem, of the second sliding area abutting on the stem guide at a position where the engine valve is fully closed.

An adjustable exhaust port 2-stroke motorcycle engine with a center adjustable exhaust valve or a split center adjustable exhaust valves includes a closing fork. The closing fork or closing arm base portion is screwed or bolted to a control rod shaft. At least one spring is disposed between a surface of an engine cylinder and the at least one transverse post of an exhaust valve. A first end of the at least one spring is in contact with the surface of an engine cylinder or a surface fixed mounted to the surface of the engine cylinder, and a second end of the spring is in contact with or linked to the at least one transverse post. The center adjustable exhaust valve or either or both of a split center adjustable exhaust valves is spring biased to an open position by the at least one spring at all times.