This has been an issue on my mind me ever since I started my first gas engine up last Saturday. The throttle response was weird! I've been doing a little research, and found this extract from Troy Built Models that summarizes the problem perfectly:-

"The carburetors on gas engines are not linear at all. At 1/2 open, they are at 85% power, and little happens between 1/2 open and fully open."

In my inexperienced words, there's an abrupt jump in rpms at a certain point (it went from about 4000 to about 6000 in about 2 clicks) as I open up the throttle and at others, there's barely any increase at all - I'm guessing this would make aerobatics pretty hard to fly.

So how do I program the throttle curve on my transmitter to smoothen out the response? I'm thinking:

#1 Identify the point at which the surge occurs (with a tacho) and then reduce the curve % at that point

#2 Increase the curve gradient where throttle response seems sluggish.

Thereafter, do I just click the throttle lever forward 1 click at a time and adjust for a uniform rpm increase?

What about expo? Should I turn it on?

Sorry, I've never felt the need to do a throttle curve on my glow aircraft engine and my only experience was a brief and passing encounter when I was setting up a heli. For info if needed, the engine is a brillelli 25GT and my transmitter is a JR 9303 equivalent (its marketed as a 9X2 here).

Will be very grateful for any help or suggestions. Thanks!