7200 with a 18 X 8 and the stock carby is doing pretty good for a Ryobi.

That is sort of the sweet spot for torque for a Ryobi. I don't think you should go to a 18 X 10 unless you cut the diameter down to 17"

There are so many variables involved here, You may try a 11.11mm carb? This would be a Walbro #28 in a Ryobi. The stock carb is a Walbro #20 (7.94mm)