There are a couple of things that can cause a kick back, including too much fuel when priming the engine.
The older software, pre-version 40, would fire the plugs at TDC when starting. It wasn't until V40 came out that they started firing the plugs at 4 degrees after TDC when below 200 RPM.
You might be firing just after TDC, as the resolution for setting the timing on the flywheel really isn't that great.
It is my recommendation to program the P-mags and set them to TDC. If you go this route, document the timing setting in your engine log book so you know exactly what they are. That way, if you ever send the P-mags back in for a checkup they will come back reset to factory defaults. Then you can reset them to your desired configuration.
Programming them is easy enough to do with the free EICAD program from EMAG; however, it will require you to buy a USB to Serial converter.
That you can rip down here to SC86 and we can do it here. All you will have to do is remove the cowls. (We are a bit far from Nebraska though.)
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC