| 摘要 |
A two-stroke engine includes an intake-and-scavenge valve in the cylinder head together with a fuel injection system, a recirculating type pressure lubricating system, and a blower or turbo charger assisting in charging the cylinder with air and also assisting in scavenging the exhaust gases . The piston head is domed with one side curving downwardly towards the exhaust port formed through the wall of the cylinder above the bottom dead center position of the piston head. The exhaust port slopes outwardly and downwardly following generally the slope of the piston to facilitate the flow of exhaust gases therethrough assisted by the scavenging air entering through the inlet-and-scavenger valve. The valve is operated by a cam mounted on a cam shaft upon the cylinder head which in turn is operatively connected to the crankshaft. The width of the cam lobe is such that the opening, closing and duration of opening of the valve is controlled with the valve being opened approximately 140 DEG and with the piston controlling the opening of the exhaust port through approximately 130 DEG so that there is approximately a 5 DEG overlap at either end of the exhaust port opening. It should be noted that the oil scraper ring remains below the exhaust port at all times to prevent lubricating oil from escaping through the exhaust port.
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