I am not an expert on engines, but I am learning.

I have an OS 46 AX and it was in a crash a year ago. It hasn't been used much as it was prone to cause dead sticks. I have been working on the engine this past week to try to figure this thing out. This is where I am at so far.

The symptoms- It will start- It idles rough, then a little throttle and it smooths out, as I increase throttle from this point, it starts to die.

I changed the glow plug. No change.
I changed the high speed needle valve assembly with a brand new one I had laying around and no change.
I tried adjusting the low speed needle, it seemed to improve a little, but basically did the same thing- no change.
I took the engine out, built a test stand and mounted it with a new gas tank and lines, no change.
I have another OS 46 on a different plane that runs great. I switched carbs- no change.
I took the carb from the problem engine and put it on the other engine and it runs fine still, so that rules out the carb..

hmm.. now I am stumped- any ideas?