Wingspam

I have 2 new 55ax motors that have 10 tanks ran thru them, 3 on the ground and the rest in the air. I am using omega 15% turning 12x6 3 blade props, these motors are on WM P-82 twin mustang. Break-in as per manuel and have done this same break in on about 20 of these motors. These 2 current motors have a very bad midrange, I have tweeked both the needles till I am lost and now I need some help...Top end rpm's are 11k low end idle is close to 4k.

I have been using the #8 Os plug but after a visit to the local hobby store they suggested an Os f plug. So I tried it but it didnt seem to make any difference.
Where can I go from here? What is the factory recommendation for the needle setting?

Help me if you can

tevans55

I don't know if this is related to your problem. I have the OS 50 and the 55. Neither ran well in the mid range until they had about 15 flights and the low end needle was set very carefully per the instructions. It seemed like I had to wait quite a while before the low end would set properly and then the engines ran great. I just ran them a little on the rich side (per instructions) until I had some flights on it and hoped it would get better. Eventually, I ajusted the low end and both engines ran great. Hope that helps.

Bax

My Feedback: (11)

Your difficulty is that you are using propellers that are much too large for the engine. You should start trimming the diameter of the props so that the peak RPM when leaned to just rich of peak is over 12,000. Properly set up, the idle should be 2,500 RPM or lower.

Try an 11 x 7 two-blade prop, or even an 10 x 7 or 8 two-blade prop. The engine will do very well if you let it turn up.

Michael7810

Did smaller props fix your problem? I have 2 55AXs on a Cessna 310 with 12x5 APC props that turn 12,900 rpm and have the same problem. Engines load up at part throttle but run fine at idle and wot. I like to fly approaches at about 1/2 throttle but afraid it will load up and die. I fly wot until ready to land, then reduce power to idle for landing. Tried the F plug also and it did not help. Looking for other suggestions or tricks to set the carbs properly.
Thanks,

traiders

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