Here's the thread on my LT-40.

http://www.rcuniverse.com/forum/m_6359162/tm.htm

I *think* I could've made the smaller motor work, but I mistakenly thought, "morevoltage can swing bigger prop faster." That was wrong...

Ithink, If I had gone with a smaller prop at the higher voltage, the original motor probably would've worked.The 11x6 I started with, was justover the edge of what the motor/ESC could handle. A slightly smaller prop, like an 11x5, or a 10x6 would've probably been within the power limitations of the motor/ESC. 11x5 would probably be the better choice. The LT-40 isn't exactly a speed deamon, so you don't need the speed of the higher pitch prop. Where-as the extra thrust 11" diameter prop would've pulled the plane around (albiet more slowly) with authority.

Then again, my current motor flies the plane really well.

I think if I were starting over, I'd try something like a Rimfire 42-60-800, an 80Amp ESC, a 5S2Pbattery setup, and a 10x5 prop. You could then keep the stock landing gear. Actually, I'll be using this setup in a 4*40 that's waiting to go on my building board.