martinoto, I just think we just giving you a warning that YS engines are a little more complex to set up and get tuned right than the saito, OS and other 4-strokes, I wished someone would have warned me and saved me the $. For sport flying with easy set up and running stay with the regular 4-strokes, but than you sound like the guy who has to learn himself. Now if you are a competition flyer than YS cannot be beat for performance.