RE: 5+5+1 Starting technique awesome!
In my experience, the key to starting the ZDZs with their rotary valves is the what happens in the second 5 of the 5-5-1 technique. However you choke the engine- ignition on til it pops or ignition off for five flips- after that you must open the choke, crack open the throttle (I don't open it all the way, just a 1/4 throttle or so) and flip it through 5 times or so. This seems to flush out any excess fuel and leaves just the right amount to start the engine. I refer to this as "clearing the cylinder"
The engine will tell you if it has too much fuel and needs to be cleared some more. If, when you flip the switch and flip over the prop, the engine gives you a single pop, don't keep flipping. Instead, turn off the ignition, keep choke off, open throttle a bit and flip it a few more times to clear the cylinder. It should be ready to start now- turn on the ignition and flip the prop.
After this, mine always start right up.