TD -1

Is the MAS 20 X 10 prop you are running a wood prop or composite prop? I find that the MAS wood are very poor props and turn 1000 rpms slower than the MAS composite props.

My 3w-42's (2 of them) turn in the mid 7k rpms with MAS composite 20 x 10 props

It has been my experience with 3w engines that the cc displacement is a good measure of the fuel consumption per minute in cc with the throttle wide open. Since there are 30 cc to an oz, fuel consumption at full bore is 1.4 oz per min.

All of my rear carb 3W engines spit fuel out the carb. (15 3w-24s, 2 3w-42s, 2 3w-50s
It is a problem with 2 stroke engines but it is most obvious when the carb is enclosed.

Elson