Hit17, I have never tried that break on a OS max engine. I only run the Fox Stunt 35. So I would guess you would have to experiment. 4 rich 2 lean 4 rich that’s the combination you have to achieve. 4 rich plane is flat flying position 2 lean raise the plane to a vertical position nose straight up. Then return to 4 flat plain goes rich again. That the 4 2 4 break. To my recollection I’ve never seen an OS engine do that. I’ve been flying a long time, just have never recalled it. On any engine, but the Fox Stunt 35. AJ