What to do When Your Motorcycle Gets into the Water
As soon as you are out of the water with your motorcycle, work quickly to remove the spark plugs and turn the engine over several times to remove water from the engine. Use WD40 to spray into the cylinders and dry off the spark plugs. Then douse your starter motor, alternator and any other electrical components with WD40. This will often involve removing your fuel-tank, so learn how to do this. Depending on the amount of water and time spent under water, you will likely need to change your oils.
Check if the engine oil has turned to a milky white color as this shows it is contaminated. This will also include checking final drive oil on a shaft driven motorcycle. Water in your fuel tank can be drained off from the bottom, as it won't mix with petrol. If you have carburettors, remove the bowl and clear any water. The refill with fresh fuel to prevent oxidation. Hopefully, you should then be good to go again...