Beej, You're welcome.
Think of it this way: Fill your fuel tank then open the petcock and drain the tank back into a can. Time how long it takes to empty the tank. Now fill the tank again and go for a ride using the advertised gas milage of most 2 stroke kits, 100+ mpg (probably more like 80). Run your tank dry and time your ride from start to stop. I will guarantee that the ride will last a lot longer than it took to drain the tank. Even with 3/16" line. I can't imagine that even a modified pocketbike motor would require more than the amount of fuel that could flow through a 3/16" line. That's a lot of fuel. Just for comparison, you can successfully feed a 300 hp small block Chevy with a 3/8" line and never starve for fuel at highway cruising speeds; and it has seven more cylinders