I understand they theory behind choke in lyc/cont. cylinders but why does it vary so much?? why did they used to be all straight bore like the rest of the internal combustion air cooled world, who got it right aircraft or air compressors???? i have seen air compressor run much longer than any aircraft engine, Is choke a half a$$ed attempt to save a step in manufacturing??? Surely someone here can figure out the expansion rate of the head vs the barrel of the cylinder. I can see one to three thousands but not ten plus.