After 1/2 to 1 gallon you'll propably have to tweak the needles,, mine was just a little rich on the low end after the first few tanks.

Try this,,
Put as small an arm on the servo as you can to max out your ATV or end points. Then cheat the servo arm position to have the arm further away from 90 degees at idle, and closer to 90 degrees at full throttle, that will give you more expo or throttle curve on the low end.

Good luck