RE: My DL 50cc is acting up AGAIN
The pill bottle, film canister, cardboard tube, balsa box all do the same thing... they act as an accumulator/damper to permit gradual adjustments of atmospheric pressure to be felt by the static port of the diaphragm. It makes a HUGE difference on SOME airplanes, not so much on others, and depends on a wide variety of variables which are somewhat totally unpredicatable.
The fact is, that many of the "conversion" gassers have side-induction carbs, whose pressure ports sometimes point directly forward, and are "impacted" by high and changing pressure air masses during various maneuvers.
Symptoms are the same.... can be adjusted perfect on the ground, as soon as climb out, either richen, or begin richening in mid range during abrupt changes in attitude. Seems to also be prevalent in "bucket" cowls like Yaks, etc., althuogh certainly happens on others.
I simply modify all of mine as a matter of course, so I don't have to wonder whether it is going to be affected or not.