Whats the difference between 4 cycle or 2 cycle hand held equipment?
That's a great question. First, I believe we must understand the 4-cycle vs. 2-cycle theory. (it should be noted that 4-cycles and 2-cycles are also known as 4 strokes and 2 strokes.) Quite simply put, a 4-cycle engine fires every other time the piston comes to top dead center where as a 2-cycle fires every time the piston reaches top dead center. To make it easier to understand I am placing links in here to view. There are several links for each and one with both 2 and 4-cycles in the same video.
4-cycle:
http://www.youtube.com/watch?v=fOojOpQ7KCs&feature=relatedhttp://www.youtube.com/watch?v=x_p3fFblLBkhttp://www.youtube.com/watch?v=L-kYu0k5lF4&feature=channel_page2-cycle:
http://www.youtube.com/watch?v=MW1jixDvUSY&feature=relatedhttp://www.youtube.com/watch?v=LuCUmQ9FxMU&feature=relatedBoth 2 and 4-cycle:
http://www.youtube.com/watch?v=viWhxvo6DLk&feature=relatedSo with that being said, the 4-cycle is more efficient per hour of operation but as a result yields less power. As at least one of those videos mentioned, a 4-cycle has more components which makes it heavier than a 2-cycle. With it only firing on every other stroke, you will obviously get less power from the engine for the same piston size since the piston can only deliver power on every other stroke.
Thus, we now have better fuel economy per hour of operation, a cleaner running machine, but at the trade off of having a heavier machine with less power. Thus, we have a much worse power to weight ratio. So if you buy the 4-cycle (aka 4-stroke or 4-mix) option trimmer (or whatever type of hand held equipment) it will run cleaner, but it will be heavier and will cause operator fatigue much quicker due to the weight. And needless to say, you can not work as quickly under sever cases as you could with a more powerful machine.
So we see the down side of the 4-cycle engine. The downside of the 2-cycle is that it does not run as clean as a 4-cycle due to the way the fuel enters the cylinder and can easily exit through the exhaust port without being combusted. However, in recent years several manufactures have employed a different port system that removed the exhaust from the cylinder with fewer chances of fuel/air mixture escaping through the exhaust port without combusting. From the specs I have seen, it appears the stato-charged (newer port system) the engine will have slightly less power than the exact same size engine without stato-charged ports. One engine with stato-charged ports is acclaimed to get up to 30% better fuel economy than the non-strato-charged engine. The Strato-charged port engines also have more parts to cause problems and is at least a little more difficult to service. The other upside to 2-cycles is that they have far less parts than any 4-cycle and thus is a much simpler machine and much simpler to service.
So just know that there are trade offs with both the 4-cycle or a 2-cycle engine. Ask yourself, should I go with a more powerful but slightly "dirtier" engine? Just know that today's 2-cycle engines are not that "dirty" anymore and exceed the standards in all nations of the world. Or, is the "greener" 4-cycle option your preference? Either way, make an informed decision. I know this is not a complete or exhaustive (sorry for the pun) guide, but hopefully it helps you understand the mechanics behind both engines and why one is better that the other in certain aspects.
It you have a specific question regarding this or anything else, feel free to post it here or send me a PM and I will do my best to answer it in a timely fashion...
-Eli
