Lubricating system for engine

Abstract

An improved lubrication system for a two-stroke engine having a lubrication path from an oil sump directly to an induction valve assembly for noise reduction. The oil sump is divided into two chambers with a restricted passage therebetween to ensure lubrication of transmission gears upon startup while reducing drag during operation. A cross-drilled lubrication passage through each crankshaft throw terminates in a second passage proximate a dead-end plug, the second passage being in communication with the piston rod bearing. Each piston skirt includes at least one axial groove in registration with an oil supply passage. Circumferential grooves distribute the oil around the piston skirt from the axial grooves. The pistons may include ceramic top layers for heat insulation to increase the compression ratio possible by raising the ring positions. The engine incorporates an air/oil mixture separator within a balancer shaft chamber and air from the chamber is directed to the intake system.

Dependencies are inferred from the claim text.