Updating oiling u ul ulh
Bill Harley and Arthur Davidson had really only figured out that when they wanted to go faster, all they had to do was make a bigger engine! There are two ways to make engines bigger: You can increase their bore (the diameter of the cylinder) or their stroke (the distance the piston moves up and down inside the cylinder).
An engine's bore-to-stroke ratio tells us something about how it was designed and how it will perform.
The easy solution to this was to let the flywheels be the lowest point of the engine, and to truck in oil from somewhere else.Because of the tall, long-stroke engine, adding an oil pan to the cases would mean either the sump would hang perilously low between the frame rails, especially considering the relatively poor travel of rigid rears and sprung front ends, or the backbone of the frame would have to be raised to make more room at the top.If the engine was moved up, the gas tank would sit another 5 or 6 inches higher, which would be no good.Engines that have nearly the same bore and stroke (a 1:1 ratio or so) are referred to as "square." Engines with a bore appreciably larger than the stroke are referred to as "oversquare," and the opposite, with a stroke larger than the bore, is "undersquare." An undersquare engine tends to be tall.
The longer the stroke, the taller the engine is to make room at the top for the travel of the piston and at the bottom for the throw of the crank.
Over the years, other manufacturers turned to oversquare engine designs, particularly in high-performance bikes.