That is nice to know that the larger bore carb works too. The carb I used is a Walbro WT-298-1 carb and it has a 7.14mm intake venturi bore in it.
I think they were running 8 and 9mm bore carbs on the 15 to 17cc engines. So I figured using a 7mm bore carb would be about right with a 9cc engine.
But if I get around to it, I might try a larger 9mm bore carb like you did and see what happens.

But when the stock carb and pump/regulator was causing my engine to flood out on me, it turned out that the pump and regulator diaphragms were going bad. I replaced them and everything started working OK. The diaphragms looked Ok though, but something was wrong with them. On another engine the diaphragms seemed to stretch out and sag more over time which caused the engine to flood out at low speed and starve for fuel at high speed.

Of course there might have been a microscopic speck of debris inside that got dislodged on me and I didn't see it.

I took a look at one of the regulators on my engine and the lever protrudes a little above the base of the regulator body. But it seems to work OK like that though.