I am writing this for my buddy because he doesn't know what is causing this.

the 400 runs great on dry land and no problems at all, but when he gets in water a little bit above the foot wells, it starts to bang out and bog like something is wrong. Soon as he gets on dry land again he is fine.

I was thinking maybe he is sucking water in the carb somewhere like a long hose hanging down?

The only mod he has on the bike is bigger tires but they are not enormous.

 

the vents for the carb are up on the handle bars and should not be getting into water unless there unhooked form the carb it self. is the electronics getting wet and causing it to run like crap ? it would be a few minutes to dry off and wouldn't come out of it as soon as he leaves the water i wouldn't think. is the belt slippping or is it the engine that is the issue? he should be usong low range alot w/ huge tires to save on his blet and clutches while playing in the bad stuff. imo