ORIGINAL: SMOKEFAN
Im tellen ya richen that bottom end. Start it and warm it up. Then hold the model nose up at full throttle and see how it sounds on top. You may need to go a click or 2 rich on top also.
What engine and what glow plug are you using?
Its an OS 40 max and to be honest, Im not sure about the plug . Im gonna have to check and get back to you. Im just using what the guy give me when he give me the plane. guess I should've paid attentionto them. My last one is in the plane in the shed. Ill look after while and let ya know.