RE: YS 2 stroke w regulator
This particular engine does not have a low speed needle, if it's the one I think you're talking about. It sounds to me as if the regulator is too rich, (pumping too much fuel) and it's loading up in the idle, then when you punch it it bogs and dies. So you need to lean out the regulator. I want to say you turn it OUT to lean, IN to rich, but test it to make sure. You only want to move that regulator not even 1/8 turn at a time though, since tiny movements make big changes. Is the screw flush with the regulator body? That's what everyone says is the starting point. The vintage pattern guys really know these engines, if you have more trouble with it then they're your "go to" guys. But try adjusting that regulator on the ground, if after idle you accelerate, it coughs and smokes, you know you're rich.