I just tested the OS FS 61 with the controlled air bleed.
First, I adjusted the engine at full throttle with the main needle, then I found the optimal idle and transition points with the secondary needle. Next, I tried to improve the entire range with the air bleed. I can see a change in engine speed when opening or closing the air vent, but in my case, the improvement wasn't very noticeable. So I tried the engine with the entire air bleed system removed, and I must say that this engine runs quite well on gasoline with electronic ignition, and that's all. So I'm going to try a flight like this and see if there's a need to reinstall an controlled air bleed or solenoid system.

Do you think a linear valve (from aquarium?) controlled by a servo, on the fuel line, could works like Bert's solenoid but with the simplicity of Cat's air bleed?