[. . . ] With its high power output and light weight, it's ideal for your TOC airplane. [. . . ] If the engine dies when the throttle is advanced, the mixture is likely too lean. If the engine stumbles when the throttle is advanced, the mixture is likely too rich. A too rich mixture will only result in poor engine performance (engine is easily off in a quick accelerating and decelerating decelerating process), pre-mature carbon buildup, a fouled plug and excessive exhaust residue. however , a lean mixture will also damage the cylinder and piston badly. After few times full throttle tests and check the spark plug, it appears to be yellow if mixture had been set tests properly. A lean set up on Low speed needle results engine difficult to accelerating, a ean accelerating, set up also results engines unstable and off while deceleration. Step 1: Close the Choke and turn on the ignition, advance throttle to full position. Step 2:, briskly flip the prop through compression until the engine fires and then dies. [. . . ] Carefully remove the pump cover (inlet side of the carburetor), gasket and pump membrane. [. . . ]