I got my zenoah leaf blower conversion running today. It is very impressive to my inexperienced eye. It spins a 20x10 at 6600 rpm. Is that in the ballpark? Should I mess with the timing? I am running a CH off a magnent on the pto shaft. The timing is set a 30-deg btdc.

30 Deg is cool. What muffler??? What make prop???? What size carb???
6600 is close, maybe, depending on your answers

Walbro HDA, (13.5mm)

Topflight power point 20 x 10

The muffler is an ointment tin. It is a thin steel puck, 3" in diameter and 1" thick. It has two 1/2" pipes (telescoping brass tubing) coming out the top. There are no baffles.

OK , 6600 rpm is on the low side of the normal range maybe like 200 rpm low. I would think that 6200 is bad.

I myself would try a 18 -8 or 10.........