05-05-13, 06:44 AM
Not necessary to drain coolant. When you remove the side covers, set aside two of the bolts. When you take off the coolant feed pipes to the carbs, just plug the ends with a bolt. 
Most likely the fuel level is high enough to cause the leak from the float bowl flange but not high enough to enter the overflow pipe.
While draining the float bowls for winter storage is good for preventing gumming inside the carbs, the downside is that the O-rings and other synthetic rubber seals dry out. I suspect this is what has caused the float seat O-rings to leak now.
Most likely the fuel level is high enough to cause the leak from the float bowl flange but not high enough to enter the overflow pipe.
While draining the float bowls for winter storage is good for preventing gumming inside the carbs, the downside is that the O-rings and other synthetic rubber seals dry out. I suspect this is what has caused the float seat O-rings to leak now.