Wobbly, my friend, the only time I ever experienced the po-go effect was on an R100/7 where the hydraulic damping cylinders in the shocks were completely sacked out. On the mono RS I used to own, I never had to mess with the spring pre-load. That bike had no issues such as you describe with yours. Again, the hydraulic damper in the center is meant to counter act the bouncy nature of a spring that is captured in a limited space with a limited range of travel. Every one knows that motorcycle shocks are stupid expensive, but the best way to resolve your po-go issue would be to fit a known-to-be-good shock in the suspension. and see if it makes a difference.

Turns out, under on-the-road observation that the spring was too weak and the shock was bottoming out. The bouncing, "pogo stick" feeling was the shock striking the rubber bumper ! With the help of my brother measuring the "sag", I increased the spring preload and this helped a lot, however the two-stage spring is now "coil bound" on the lighter side of the spring, thus negating its effectiveness.

In discussions with shock guru Ted Porter (Ted Porter BMW), he does not recommend dual-rate springs for the single-sided bikes. The gases in the shock itself act as the first stage compression spring. Ted is an Ikon dealer, so this is not simply "sales talk".

In my personal analysis, the Ikon single-sided has a total shock movement of ~35mm (1.37 inches), so there is not enough stroke or linear displacement for dual-rate springs to have any effective action. So Ted's point is easy to see.