I am posting this for my girlfriend, she has a z400, and I have a predator. we went riding yesterday and she got stuck in a little mud puddle-it was only about 12" deep. It didn't stall right away we went down the trail and it started poping, coughing, and backfireing and then eventually died. It would only start with the choke on but when you gave it the slightest bit of gas it would die. I thought that it might water in the gas but it didn't. After I toed it home and it dried off I started it and ran fine. I washed it after and the same as before.
It sounds like electrical problems but what coil, cdi, what?

 

I would think the same thing coil or the CDI.

 

take a hose and spray 1 component at a time. Ride it and see if it dies, if not go to the next component.

 

Sound like your coil wire is getting wet. Its not getting enough spark to burn the fuel when you throttle it. Check to make sure your connections are tight on all your wires. Just a thought, but it could be numerous things...

 

mine goes alot slower when i go threw water but is fine in muc when i go threw water it kinda bogs on me but never stalls

 

The problem is in the spark plug coil cap take the cap out and blow it out . Then be sure to put high temp silicone around the stupid hole that suzuki has for the plug the water usually boils out of the hole but not the inside of the cap. We had the same exact problem. I'll bet anything thats it.