if you mean fuel mixed with the flywheel and stator then it's the seal behind the stator but not sure why you would have that much fuel to leak out of what would have to be a very damaged seal. You will need to pull the flywheel and remove the stator to replace the seal.
Or,
Do you mean fuel in the crank-case? Some may be considered normal as fuel comes from the carb and is pulled into the crank-case (lubing the crank and rod bearings) before being pulled to the top-end to burn (that's how a 2-stroke operates). I know I have pulled my crank-case drain plug (not tranny drain) and have had 1 or 2 teaspoons fuel dribble out sometimes but when that has happened it's usually because I had a carb problem and the bike wouldn't start.