Carburetor performance trouble?

i race in the IWA waterX (snowmobiles racing on water) anyway when i go to take off my engine is laggy then it picks up as if its getting to much fuel cause when i take off its fine then once i hit the water it bogs down and i sink so i was wondering whats the problem cause im not a big engine know it all ha ha and where can i find o rings for my carbs because i need new ones i was told by a few other racers thanks