I make a 26cc lightweight conversion, 2 1/2 lbs, powerful, relatively inexensive (?)...It's called a Zenoah G26..I don't have anyone beating down my doors or buying truckloads...
As for a 25cc DA, don't hold your breath..It would cost almost as much to make one that size as it does to make the 50, except for a slight reduction in the cost of the aluminum for the case..Machining time would be slightly less, but carbs and ignitions all cost about the same, regardless of size..Cylinders and pistons ? buying in quantites of 500 or more to get a good price is $$$$$$...Unless Dave wins the lottery I wouldn't hold my breath or engage in idle speculation....
We all saw what happened with the BME Extreme 55...Lesson learned....[8D]
What's not lightweight, powerful, or reliable about a G26..Ever have one ?