As long as you don’t drop the bike or the water don’t reach the exhaust you should be fine. if the bike stall’s or gets water logged get it to dry land, remove the spark plug and dry it, turn the engine over a few times to clear any water, replace the plug and off you go again.
if you go through water often though always keep an eye on the oil, if you start getting a white goo on the oil filler cap, this meens it is contaminated with water. drain the old oil out, then flush it with something like paraffin.

As long as your engine is sealed good, and no water gets in your air box or over your exhaust tip everything should be alright. I have done this many of times with a kx250.

If you get water in the engine it will Die . oil and water don’t mix

I would imagine that they can get them dried out and reuse them. But it can’t be good for them.