6 to 8 years ago, Model Airplanes News did a .61-sized engine shootout. As I recall, the OS .65LA out turned the OS .61FX on every prop except the 11-7. They were close, as were all the engines, but the .65LA was surprising.

I bought 2 of them and have never regretted it. They are fine running and reliable engines despite the air bleed carb. They tune up easily, run strong, never quit and rarely, if ever, need tweaking. They run so well, my flying buddy, who is 89, snagged both of them for use in scale planes.