I flew my Stearman last weekend for the first time. Power OS 120 w/Pump. Zinger 16x5 prop, Slimline inverted smoke muffler and sullivan pump
I had to add some down trim on first flight but other than that, no problem. Aircraft flys very gentle with control throws set at recommended rates. I will set the rudder with additional throw for future flights.
As to the differential throw on the ailerons, I had a similar problem. I resolved it by experimenting with location of lower slave horn. I had to reposition it somewhat, maybe a quarter inch or so. I also had to shorten the slave struts about a quarter inch. I was able to eliminate the binding and although the upper and lower aileron travels are different, the aircraft flys very well.
I also did not have to add the 18 oz. nose weight the manual mentions. I did put a smoke pump mounted in front of the firewall, but that only weighs abt 3 oz.
By the way, the smoke system works great as the aircraft is not very fast and the smoke stream is not diluted by speed.
Very impressed with the quality of the aircraft, fiberglass, painting and covering is excellent.