I agree with the above statements... The part you do NOT want to get wet is the magneto coil under the left side cover, but you also don't want any water to sneak into your gas tank either since these gas caps don't seal that well. The carb is vulnerable especially if you got one of those K&N clone filters, and of course, the throttle cable can drip water into the carb or make your cable start to stick or bind after prolonged exposure to the elements.
Best thing to do is cover it with a plastic tarp if you have no way to store it indoors or under a roof like in a carport etc...