Well the eflite 25, with a 4s battery should fly a 4 pound (64 ounce) plane with ease. It should be putting out some where around 5.25 pounds of thrust. So it is over powered for the Cud and the small 2 pound plane.

I use this calc tool.

http://www.s4a.ch/eflight/motorcalc_e.htm

This little motor on a 3s battery turning a 10X6 prop will fly the 36 ounce plane

http://www.e-fliterc.com/Products/De...rodID=EFLM1505

Or this one

http://www.hobbypartz.com/75m21-opti...10-1020kv.html

I too was going way over kill on the motor battery size. I have learned that sometimes smaller lighter is more power.

The 3s 4000 is a little big for the Cub butt will work. Just more weight to fly around. You will get real long flights with it.

Buzz.