if i am picturing this correctly, you hooked the drain tube to a brass tube near the rear of the carb opening? like right by the air fiilter?
if you did that, it's bogging because that rear tube on the carb is vacuum, and it is sucking extra gas from the drain into the carb, making it run WAY too rich. if your drain tube is leaking, that extra gas is just being sucked right back into the carb without being atomized. it would be the same as just dumping a spoonful of gas into the carb...too much and it will kill the engine (too much gas, not enough air). a precise amount of gas is sucked through the main jet where it is mixed with the air inlet charge and the mixture gets atomized for a more efficient burn. if you add more raw gas to this mixture, it will bog or kill the engine.
on the other hand, if you hooked the drain tube to a vent tube on top of the carb, you may have created a negative vaccuum in the carb by blocking off the vent.
i am not exactly sure where you hooked this drain tube, a picture would be helpful.