5 hp rotavator fires but will not run,is it the carb?

i picked up this old rotavator the other day,i then stripped cleaned and put her back together. The carb and piston were full of water,via the air filter housing. I put new oil in and fuelled up,i also put a coupleof drops down the carb. It fired and ran for a few seconds then puttered out. what should i be looking for and how can it be repaired?The only info I can get off it is that it is a I/C industrial commercial engine, cast iron bore,5hp, quiet power.