As I was getting ready to drive the 914 to work, for the first time since I rebuilt the motor, I checked the oil and noticed beads of water on the dip stick. It rained pretty heavy yesterday and I belive water got in vent on the oil fill tower. Am I screwed? Am I going to need to pull the motor back apart?

No, you do not need to take the motor back apart. You do need to keep the water from getting in though if at all possible. It is normal for water that is suspended in air to come out of suspension in your crankcase. This is why you hear people say that your oil temperature needs to reach at least 220 degrees. The boiling point of water to get it out of there.
Change your oil at least every three months even if you don't drive the car much and always start the car and warm it up well at least once a week if you are not driving it daily.
By the way, if you are talking about a quart of water in your crankcase and not just condensation on your dipstick you need to get your raintray back on!

Thanks for the help. I would love to put the rain tray back on but I have carbs on it. Is there a rain tray that fits with carbs?

Check in the member vendor section. There is an option called rain hats. they are basically just a top that goes over the air cleaner and routes water out and away from the air cleaner. Your engine should be otherwise sealed against mass amounts of water. There is nothing you can do and it is normal for condensation to form. Just make sure your trips are long enough to get the engine over 220 degrees for at least a few minutes. This is part of why they tell us our short in town trips are hard on motors.
Charles Navarro has put together the most readable information I have seen on engine oils and particularly aircooled engine oils on his site and he frequents a lubrication forum on Jake Raby's site. Good information.

Carb "hats" are readily available from one of us (Morph), and the breather/filler assembly, by law, is supposed to be vented into the air cleaner. (It's been the law since 1965.) If that's done, there's no way water can enter the closed system, unless maybe the car's submerged!

The Cap'n

what type of carb setup do you have that won't allow for the raintray? i run weber 40s, cb tall manifolds, and 3" tall filters. my tray fits. i would invest in one of perry kiels 'umbrella' covers. they will keep the rain out.

k

I have carbs, the rain tray fits with no problem

I had an engine that took in some water through a carb when sitting outside. Took in several quarts of water. I drained the oil first which was good since oil floats on water.

If you took in a lot of water, it could be sitting below the oil and will be sucked through the pump and into bearings instead of the oil. You may want to change the oil if you think you've taken in a quantity of water.

Spoke

Yep. Be safe and change the oil since you don't know how much water might be in there. Then fix it so no future water can get in, and you're all set.

How far is your commute?

Condensation is a real occurrence and can cause water in the oil, especially if you're not driving it far. ConeDodger is right. Change the oil and pay attention to how much water is actually in there, then decide if you have an issue, or if this is 'normal' operation.

Rain hats are a good idea too.