About the phenomenon; I have seen this happen; you throttle down and the engine hangs at 4,000-4,500 RPM for some 10 seconds, before dropping to idle...

I think the engine I saw do this was too rich on the low-end mixture.

In most cases, this only causes a fading idle and a 'burbly' recovery to max RPM (if it eventually happens), but that engine had that 'hanging' before drop-down.


Mick; it certainly is not a nitro related problem!