Scavenge system for two cycle engines

Abstract

A number of embodiments of two cycle crankcase compression internal combustion engines having at least two cylinders in a common bank in side-by-side relationship. Each embodiment incorporates a main Schnurle type scavenging system that includes a pair of main scavenge passages on opposite sides of the exhaust passage that terminate in main scavenge ports that are disposed in proximity to and on opposite sides of the exhaust port. A transversely extending supplemental scavenge passage is provided for delivering a charge to the combustion chamber to somewhat restrict the scavenging flow so as to prevent fuel from passing out of the exhaust port. Fuel is injected into proximity with this supplemental scavenge passage. This facilitates stratification of the fuel charge. The ports are rotated from normal around the cylinder bore axis in many embodiments to provide a more compact construction. Even in those embodiments where this is not done, the fuel injectors are mounted so that they can be easily accessed from outside of the engine body. Various applications for the engine such as a motorcycle, personal watercraft and outboard motor are depicted.