I have a brand new ultra stick 40 in need of a powerplant. I am wanting to go two stroke. The choices at the hobby store near me are OS, MVVS, and Magnum. I am a little more patial to the os. but am open for ideas and opinions..

I don't have a lot of experience, but would suggest the O.S. 46FX
Never had any problems with mine and it's user friendly.
Been flying for 7 months.

Any of those motors should be a good match for your US40. We've used the OS 46, OS 50 FSR (no longer manufactured), and OS 50 SX with very good results. For a little more power, the 50 SX has a slight edge over the 46... but for overall reliability and price, it's difficult to beat the 46 FX.

-Juhan

ps: http://archive.ncsa.uiuc.edu/Cyberia...l/rc_us40.html

Irvine .53 -- best engine in its class! My Irvine 53 is every bit as reliable and user friendly as any O.S. .46FX, but has a LOT more power!