The Kwik Fli dance is an interesting aerodynamic tendency that also applies to a number of other 60s and 70s designs. It tends to happen mostly in heavy turbulent air. My current Howard Engineering Kwik Fli III taper wing with retracts does not seem to have the trait but with the modern 61 engine it may fly too fast and does not have the very long standard size Kwik Fli III canopy. I’ve thought for some time that it is related to the canopy and vertical stab air flow.