AMB,

I tried an unbalanced prop, but with unbalance on the
blade so far from the crankshaft, it was very RPM
sensitive, with the lowest vibration point at one
particular speed. This would work on a control
line plane but not on RC.

I ended up drilling a hole in the prop hub
(on the prop, not on the engine prop drive)
and sticking some lead in it. I also ground as
much extra metal as I could from the pin
side of the crankshaft. Together this was
an improvement, but not as good as a
properly balanced engine.

Jenny