Zenoah = flying brick. They were once top of the line. In fact, I have a g-23 that I love. Very reliable, good running engine, but they are heavy, heavy, heavy. Do yourself a favor and go with one of the newer designs. Zenoah hasn't changed their crankcase design, which makes them heavier than their competition. My brothers G-38 is almost a lb heavier than the 45 he just ordered from CRRC (or some similar company). Those are basically all chinese engines and are almost all alike.
And they run good too!