During the four-stroke cycle, you might find that the
exhaust stroke is not fully successful some of the exhaust gases remain within the cylinder, which might mix with the incoming intake charge.
meaning that the mag doesn't fire into the
exhaust stroke, but it does fire into a fuel/air charge that's already well into combustion.
Thus during the
exhaust stroke there is a chance for the exhaust gases to escape from the combustion chamber which increases the volumetric efficiency of the engine.
The
exhaust stroke occurs when the leading decreasing chamber volume (as the chamber moves uphill) forces the exhaust out, starting the cycle anew.
The
exhaust stroke cam profile has changed for required position of the follower under acceleration and retardation motion.
They operate on the same 4-stroke principle as your car engine or other 4-cycle engines, that is, intake, compression, power and
exhaust strokes, The Gade difference is that it does not have a traditional
exhaust stroke where, after traveling to bottom dead center on the power stroke, the piston pushes the hot burned gases up out of the top of the cylinder on the
exhaust stroke.
The inlet valve opens 4.5deg before TDC during
exhaust stroke