Seems like on the smaller engines they do work ok with the exception of the 52 magnum,MY 91 FX as stated above has no issues either but my larger glow engines are a mess ,due to not enough tank pressure .
Today I made new tube ends and only opened the holes to 5/16 dia this seem to work, I had needle adjustment plus I didn't seem to lose much in RPM's .Its still 4 turns open on the top but it will get rich now ,before I could turn it all the way out with no change to the engine.