Hi,

The actual size of the carb, and what you measure, is the smallest diameter that you see inside the carb throat. If you look inside the carb, you will see that it necks down at one point. That is where you measure it to get the size.

Also, start with the needles both at about 1 1/2 turns open. Then adjust the "L" needle for a good idle and transition to 1/3 throttle. Keep adjusting it slowly inward until the engine hesitates when you jazz the throttle to 1/3 open. Then open it back up just until the hesitation goes away. Then adjust the high speed needle for max rpms, and then open it back up about 1/8 of a turn. Finally, check your idle and transition again. If it's good, go flying! If not, touch it up, then check the high speed once more. It is important to do it in this order, as the low speed needle affects the high speed setting.

Good luck,
AV8TOR