I always found water in my 81SH's carb bowls. I believe it comes from condensation due to fuel evaporating around the main fuel nozzle. With the Virago I have never seen water droplets in the bowls. Comparing the two bikes, the Virago has a very long air path from the air filter to the carburetor. So draining the fuel from the bowls should stop any water appearing in the XS carbs.