ok now that I am more clear on your install.... Lets get to the carb
1. these carbs are extremely sensative to minute specs of trash, when your son I believe is what you stated flooded the engine with water unless he jumped into a pool the water was dirty
2. the first passage the water will take is through the filter then the carb sucking into the engine choking it off the second passage is through the exhaust when it dies.
3. remove the carb completely dissassemble it remove all the o-rings and hoses. Remove the pilot (air) screw spring and o-ring there then the jets.
4. Thouroughly spray the ever loving piss out of the carb and all it's orfices the take your blow gun and blow it out real good.
5 grab a tiny single strand of wire like speaker wire and clean the slowjet the orfices are to tiny for torch tip cleaners, ust those for the main jet.
6. re install everything in reverse order, turn the pilot screw in until it seats and back it out 2 1/2 turns. install it and start her up and see how it goes