this was taken from this link
..there is an animated picture also...after you've read all this....here's the answer to you question.....A 5 port motor has 5 ports.....a 3 port has 3....the extra 2 ports add a performance boost....
From Wikipedia, the free encyclopedia.
The two-stroke cycle of an internal combustion engine differs from the more common four-stroke cycle by having only two strokes (linear movements of the piston) instead of four, although the same four operations (intake, compression, power, exhaust) still occur. Thus, there is a power stroke per piston for every engine revolution, instead of every second revolution. Two stroke engines can be arranged to start and run in either direction.
Two-stroke engines are used most among the smallest and largest reciprocating powerplants, but less commonly among medium sized ones.
The smallest gasoline engines are usually two-strokes. They are commonly used in outboard motors, high-performance, small-capacity motorcycles, mopeds, scooters, snowmobiles, karts, model airplane and motorized garden appliances like chainsaws and lawnmowers. In each application, they are popular because of their simple design (and consequent low cost) and very high power-to-weight ratios (because the engine has twice as many combustions per second as a four stroke engine revolving at the same speed). For handheld devices, they also have the advantage of working in any orientation, as there is no oil reservoir dependent upon gravity.
Two-stroke cycles have also been used in diesel engines, notably opposed piston designs, low speed units such as large marine engines, and V8 engines for trucks and heavy machinery
Various two-stroke design types
To understand the operation of the Two-stroke engine it is necessary to know which type of design is in question because different design types operate in different ways.
The design types of the two-stroke cycle engine vary according to the method of intake of fresh air/fuel mixture from the outside, the method of scavenging the cylinder (exchanging burnt exhaust for fresh mixture) and the method of exhausting the cylinder.
These are the main variations. They can be found alone or in various combinations.
Piston port is the simplest of the designs. All functions are controlled solely by the piston covering and uncovering the ports (which are holes in the side of the cylinder) as it moves up and down in the cylinder.