syzyguy
50cc
I am using PowerHD 8309's ... 150oz-in servos (at 6v) ... and they are taking care of things just fine so I think your servos are up to it. I did need to do a lot of linkage adjustment to get the two elevators to move exactly the same all the way (using the elevator leading edge as a distance measure, not the angle) through the full motion without any slop anywhere. If there was any subtrim on one and not the other they would not be perfect. My CG is around 5.25" at 3/4.
One common cause that this is a symptom of is the tail surfaces mis-aligned with the wings. Sitting in a box in a warehouse for a couple years can cause a little warping. Do some visual or and careful measurement of the distance from reach wingtip to a table and each elevator tip to the table, as well as wing tailing edge at the root to elevator surface edge. Both sides should match. While you're at it check that the rudder is a perfect 90 degrees and the tip is equally distant from each elevator and wing tip. If one side of the elevator is angled up a bit or forward a bit then greater surface deflection will cause more reaction on one side and give you a roll. If you do have a twist you can often get rid of it with a little covering iron tightening on the longer side, but you may need to shim surfaces or sand.
One common cause that this is a symptom of is the tail surfaces mis-aligned with the wings. Sitting in a box in a warehouse for a couple years can cause a little warping. Do some visual or and careful measurement of the distance from reach wingtip to a table and each elevator tip to the table, as well as wing tailing edge at the root to elevator surface edge. Both sides should match. While you're at it check that the rudder is a perfect 90 degrees and the tip is equally distant from each elevator and wing tip. If one side of the elevator is angled up a bit or forward a bit then greater surface deflection will cause more reaction on one side and give you a roll. If you do have a twist you can often get rid of it with a little covering iron tightening on the longer side, but you may need to shim surfaces or sand.