I got real tired of this engine too. Having it in my comp-arf 2.6m. Must have teaked it about 100 times and still not working right. Exact same problem as described above and worse, keep quitting in the air, extremely poor throttle transition. Dead stick during hovering, almost crash my comp-arf extra many times. Made my comp-arf extra flies like ****. All 3 other members in the club have same engine, same problem and worse. Guess what, they all got rid of the engine. I'm in the process of ripping out this damn engine and replace it with a DA100. What really pissed me off was everytime I want to tweak the needle valve, I had to remove the cowl due to the awkward location of the needle valve (hidden below the muffler).