Tuning the OS 46 AX engine
I have four OS 46 FX engines and am very familiar with them. Great engines. My new engine is the OS 46 AX and I am using the standard muffler supplied with the engine. The manual for the FX engines suggest having the mixture needle(low speed needle valve) 1-1/2 turns open and the high speed valve about the same. On the AX engine the mixture screw (low speed needle valve) is to be only 3/4 turn open, and the other valve is to be the same as the FX. After more trouble tuning my new AX engine than any other OS engine I have ever had, I have the low speed valve at about 1-1/2 turns open, which is a long way from the starting setting of 3/4 open. All of my OS 46 FX engines ran at the factory setting and required only small adjustments from that. I am asking others who have the OS 46 AX engine to please let me know how many turns open they ended up with on their low speed needle valve of their AX engine. I'm only interested if you are using the standard engine muffler. The plane my engine is on formerly used an OS 46 FX engine. The prop is an APC 11 X 6. Thanks.