I think of these motors more as "evolution" from the 66cc motors. Most (general) complaints about the old 2-strokes were noisy, leaky head gaskets, bad balance at high rpm, etc.) From what I've heard, the "100s" have addressed a good deal of those problems. No more head gasket, larger displacement and tuned to produce better low rpm power so that a person isn't getting into the buzzy higher rpm. Give the hot-rodders some time with these engines, and I'm sure they'll find the hidden horses.