Actually, they don't.

The crankshaft is immediately under the carbs of most 2cycle engines that're sold today. And the crankshaft has a hole in it. When the crankshaft turns it opens the hole for some degrees of rotation and that's the intake part of the cycle. When the hole isn't open, it's closed. And that "delivery pipe" isn't filling up. Matter of fact, it's not even collecting residual from momentum of the gasses.

With the 4cycle and it's long delivery pipe, there is an actual delivery pipe that is obvious for all to see that goes from the carb all the way to the head of the engine. It's a pipe with no flow control that stops gas flow for the majority of each rotation. With the 4cycle that long pipe goes to the head and when it gets there there is also an area inside (pull your carb/delivery pipe and look, you'll be amazed) that has more volume itself than the very small area between the carb and crank of any 2cycle. And THEN you get to where the valve sits, closing off that long pipe and large intake area under the head.

The difference in available flooding area that's shut off by the intake valve is huge. One is almost nonexistant and the other must be what? 10X? 20X? larger.

Thanks for focusing on this, because I'd only mentioned the pipe, and the area inside the head also contributes to "flood holding area" and is large and should have been mentioned.

BTW, lest we forget, when the 4cycle is turned upside down, that pipe and head is acting as a receptical roughly TWICE as often as the 2cycle. In fact, the 2cycle is open then closed each revolution. With the 4cycle, it's open then closed one revolution, and then closed an entire revolution before opening again.

Yeah, there really is a large difference with 4strokes. Both the "floodable" area AND the amount of time it's collecting "flooding".