Sorry, I don't have any pics to document it, but I have seen/encountered it many times. Even a glow engine will do it. When it is idling very rich, you will notice the engine slowing down more and more. Then when you give it the throttle, it will blubber and sputter way rich until it has used up that accumulated fuel in the crankcase. As a matter of fact, that is why the idle bar glow plug was invented. The rush of fuel from a semi flooded crankcase would douse a normal plug after low speed rich running, followed by acceleration which made the mixture go way rich. The idle bar prevented that raw fuel from hitting and cooling/dousing the glow plug.

The same thing can happen with an auto engine fitted with a carburetor on a very cold start. The fuel falls out of suspension and puddles in the intake manifold. That makes the idle/slow speed mixture lean and the car stumbles lean and has trouble running. Then, when you accelerate, the rush of air vaporizes some of that puddled fuel, and then all of a sudden the engine is too rich. Baffling to trouble shoot for mechanics that don't understand what is happening. It is especially problematic on hot rod cars that have had the manifold heat blocked off, and are running an aggressive camshaft. The problem is not very often encountered now with modern fuel injection.

So, back to gasoline model airplane engines. Just try it sometime. Set your idle mixture about 1/2 turn or so too rich, and then let the engine idle for a while. You will notice it slowly slowing down. Then, accelerate rapidly. The engine will go very rich, and stumble and four stroke and burble until it has burned up that accumulated fuel in the crankcase. The rush of air and turbulence from higher rpms "scoops up" that fuel and puts it back into suspension, causing a momentary very rich mixture. (This experiment will only work with the cylinder oriented upwards.)

I have a flying buddy that has an airplane with an upright cylinder mounted engine and a combination of a too rich midrange/idle, and a too small prop on the 25cc engine in his plane. You can hear it going into an on and off four stroke mode when he is putting around at half throttle. Then, when he inverts the airplane, it puts out a big puff of smoke, four strokes for a bit, and then cleans out. It is that accumulated fuel in the crankcase getting suddenly mixed into the moving fuel/air stream in the engine. It kind of makes me crazy, but he is happy with how it runs and doesn't want to fine tune it, so who am I to worry about it?

Anyway, it is just a fact of operation of two stroke engines, and sometimes with four strokes too. That is why polished intake ports on four stroke engines are no longer the rage. Now it is understood that some turbulence in a four stroke intake tract helps keep fuel from falling out of suspension, causing carburetion problems.

Now after having gone through all that, you'll probably tell me you were referring to the ram air problem! However, that has been well documented here in the forum many times.

Edit: Well, I tried to post a couple of pics of a carb modified for sensing pressure from inside the fuselage in case that was indeed your question, but the photo posting function for RCU is on the fritz.... AGAIN!! [:@]

AV8TOR