I just installed some new handlebars on my 2012 Fatboy. During the installation, I noticed a little bit of brake fluid around the front brake master cylinder reservoir. I took the cover off, and disassembled the gasket from the cover so I could do a thorough clean and dry job using denatured alcohol. (To disassemble the gasket/cover assembly, simply push the level indicator partially up from the bottom of the cover until the level indicator is loose. Then pull the gasket along with the level indicator away from the underside of the cover until the gasket separates from the cover completely.) After the cleaned parts were completely dry, I then reassembled the cover and gasket assembly.
Now for my solution to stop the leak. The cover has two breather holes to allow air to escape. Obviously, if the reservoir is over filled, air pressure will push excess fluid out these holes. That is why it is important to thoroughly clean the gasket and cover (every nook and cranny). The manual tells you to fill the reservoir 1/4 to 1/2 inch from the top of the reservoir, or something close to that, depending on the model. Here's the problem with that; when you park your bike, it is customary to turn your front wheel toward the jiffy stand to provide maximum lean and stability. When the bike is in this configuration, the reservoir is tilted in a manner that the brake fluid is flooding the left side of the gasket. Over time, this permeates onto the outer edge of the gasket and to the breather holes. One solution is to never lock your handlebars towards the jiffy stand when you park your bike. I don't like this solution because this leaves your bike in a less stable configuration and could result in a tip over. What I did was remove sufficient brake fluid so that when I turned my handlebars full lock, fluid would not run over the edge of the open reservoir. I removed the excess fluid using a piece of clear plastic hose and gently dipping it into the brake fluid, letting the fluid fill up in the hose, putting my thumb on the other end, and then removing my thumb and letting the fluid in the hose drain into a cup. Once I removed sufficient fluid, I reinstalled the clean and dry cover/gasket assembly and took a three hour ride. No brake problem, no brake fluid leak problem. Tonight I'll find out if I have a parked bike brake fluid leak problem, but I am pretty certain I will not.
Now, my fluid level indicator does not function because the fluid level is too low. But the fluid level is still substantially higher than the master cylinder, which is the main thing. Anyway, this is what I did to solve my leak problem. Let me know how you feel about the level of the brake fluid not being according to HD direction and any pitfalls you may know about.

 

Exact same issue. Just spend the $30 and get the new cover. The gasket is much firmer.

 

Just another problem Harley knows about, but prefer not to talk about...................... Changed mine with less than 1200miles on it

 

Think if you look close, you will find the actual fluid is not vented. What you have is a slit in the top 1/3 of the gasket that goes to the diagram bellow on the top side toward cover. What happens is it lets that thinner area pull down into the master cylinder. When the cap is on and the screws snugged, the actual fluid is sealed. If it was not, it would leak out on the tank when the bars are turned so it's over tank when parked. It's real easy to over tighten this cover. I simple go down till I see the gasket just start to bludge. That is all it takes. I installed a brake light switch the other day and mine take about 20 in/lbs to see it bludge.

 

Wouldn't my 2012 have the new gasket? I have actually watched very small amounts of fluid exit the breather holes when actuating the brake lever.

 

You missed this in the factory manual...this is a "feature"...NLOL...Supposedly if you over tighten the gasket it will leak. Mine has always weeped a little, eats the paint on the unit. I also tried to buy a new gasket and ran into the same horse hockey...It used to be available without the cover, which is how a reputable manufacturer would make it available for their Customers who bought their expensive optional products...

 

Rodzilla,
Hopefully I caught mine in time before the paint was compromised. I also checked the rear brake fluid reservoir and it also had leaked all over the engine side of the reservoir housing. I removed some fluid from that, also. Now, neither of my reservoirs have fluid above the bottom edge of the seal when parked and handlebars locked toward the jiffy stand. So far, no leaking overnight and no weeping during a three hour ride. We'll see what happens over time.

 

As others have said clean everything really well with denatured alcohol. The chrome covers seem to leak less.

 

My 2012 was seeping also. They replaced it under warranty. They said it was a common problem on 12 models and they had replaced many.