As I remember from the hazy past, a reference book said that the bore limit on a gasoline engine was considered to be 4.0 inches. Once that was exceeded, the flame front would begin to weaken. Many early engines exceeded that and that's where the guide originated. I can't remember if it was also cited in a Smokey Yunick (genuflect here)book or not - he did tons of experimental engine work. Anyway. it's not that you CAN'T, it's simply a case of diminishing returns. I wonder if things like electronic fuel injection stretch that limit now, because that 4" figure assumed use of a carb.
