I'm wondering; assuming you have a 39 jet in there now, and you put in the 56, that's a 106 % increase in area, but why wouldn't you want to change the low-speed? If you have a 19 jet in the low-speed now, and you want to increase it by about the same percentage, it would take a 27 jet.
A change from 26 to 27 on the low-end is about 8% change in area. A change from a 55 to 56 is a change of, about, 3.6%.
For sure I don't know which way to go, but information is information. More information can't hurt.
We're going from gas to methanol and changing bore size for this application. I recommend .031 for the low and this is based of many dyno pulls and data from customers all over the country. I'm very familiar with "surface area" but never take into consideration when testing and tuning of carbs. Not saying it doesn't work or isn't a good tool for you as I have some tools I use when calculating bigger carbs on fuel and air that most would find extreme but saves allot of time when it's an application we haven't built any data on.
Thanks for help guys..building my first uskra engine..I said idle in post but meant low speed bout these rules for uskra..:)
I like my pilots around .029"-.032",(altitude-sea level- 1000') but as AL will tell ya , You need to know your air density. Altitude is a good second guess..