If that is a black plastic Victa 2 stroke carburetor, it should have two wires going into it. The only purpose of those two wires is to stop the engine when they touch each other inside the carburetor, when the speed control is put into the stop position. If you have permanently connected one of them to ground, either it is the one that is permanently connected to ground anyway, so it doesn't matter, or it is the one that only connects to ground in the stop position, in which case you shouldn't have any ignition at all, not even enough for pops and smoke.
I suggest you disconnect the wire from ground where you have grounded it, and try to start the mower. If it starts and runs properly, turn off the fuel to stop it, and talk to the plastic carburetor guys here about how to reinsert it into the carburetor successfully.
