Cowboysam9970, The plane is rated for a 60 2 stroke, OS 71 should be equal, suggest using a 2 blade prop initially.

The 3 blade on mine works great. Ironically it's the same prop I used on the Saito 82A and it flew great for two years.

I yanked the Saito to put it in a Han 9 Toledo Special, flying that also on a three blade. I believe the X 500 flies better than the Toledo! Toledo has a problem with knife edges but the X500, no problem. I have flaperons on both and the X500 is better at slow speeds.