Although we all want there to be a simple formula for converting jet sizes from a low powered industrial engine on gas to an engine turning twice or more the rpm on methanol, the fact remains that there are other factors affecting the signal at the jet, which ultimately determines jet sizing.
Four cycle jetting is affected by factors such as carb size, air filter arrangement, camshaft overlap and duration, and exhaust arrangement.
The carb itself has several factors which help dictate final jetting.
The act of doubting the area of the jet does not insure fuel flow is doubled, as the signal must now act on twice the area, lowering flow rate.
It must all work together to make jetting most correct across a wide rpm range.