Finally tore into a GS I bought last year and found a nasty surprise. I bought it as a non-running bike but I did check the compression before I bought it. It has been sitting outside since before Christmas. When I started messing with it today the engine was frozen. A little muscle and I got the engine to spin. Tearing it apart I found the last person that worked on it had hooked the tank drain hose to the upper T on the carbs. My best guess is when all the snow melted that was burying the bike, some of the water went into the gas cap area, down the tank drain, into the carb and ultimately into the cylinders. I hate surprises....
-Jessie