I have bought several used engines. Most recently an Evolution 35GT gasoline and a Saito 125. I bought them here in the RCU market place and both engines are great. The Saito was "new in box" so that was a no brainer. The Evolution was used but for the most part someone with an engine like that has figured out what they are doing by now... At least you hope. I speek to most of the sellers over the phone before I buy and my favorite sellers are those 50-60 year old guys that treat their engines as they should be. I would say at least half 14 or so engines I own were bought used.