Villa

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.

ChuckW

I have two .46-AX's, a .55-AX and a .75-AX. all have ran great right out of the box with very minimal tuning required.

On both .46's I really couldn't tell you how many turns out the low speed screw is. Basically, I just leaned both of them from the factory setting about 1/8-1/4 turn after the first 1-2 tanks of fuel and haven't touched them since.

The .46-AX is almost always an outstanding, user-friendly engine. What you are describing doesn't sound normal. You may want to look for another problem or send it in for repair/replacement.

Villa

Hi ChuckW
Thanks for your input. Hope to get more comments. I use the engine on my new Canard as a pusher. The fuel lines are very long and I am forced to use a small day-tank right next to the engine, because the main tank is further away. Been doing that for 4 years, but with an OS46FX engine. Is it a typo in the manual that on the AX the initial mixture screw setting is only 3/4 turn open but on the FX it was 1-1/2 turn open?

Flying freak

Header tank?

flipstart

I have 2-FXs and 2 AXs-same easy tuning on all 4-run on test stand, lean out low end slightly and rock on. I have never checked to see how far they are out. I would email Bax on O forum and ask him what to do. He can give you the # of turns, try that, if no go, send it back.