I took my air cleaner off and this bolt (pictured) was in the air cleaner. This is the first time I've disassembled this since I bought the bike last June. It is about 1.5 inches long and the "nut" is part of the bolt (immovable). Anyone know?

 

stud of some kind????

 

Might be a breather bolt, hard to say as HD has used many different versions.

Hobe

 

That looks like it was part of a previous project by the previous owner. like a bolt that threads into the head & a different breather would bolt onto that stud. I don't think it's part of your current set up. Just misplaced in the breather while it was laying on the bench.
Hatch.

 

That's a pocket bolt. Any project you complete will have one (1) bolt left over. You put it in your pocket.

It appears the previous owner of the bike did some work on the breather and was unaware of this important final step.

 

LOOKS LIKE A BANJO BOLT!!screws into the head and other side holds aircleaner base plate!! i "think" thats what it looks like to me!

 

I've got several pocket bolts that I never knew what to do with. Thanks for the explanation. Now they're going to the correct place.

 

 

That's the same kind of bolt that holds my rear brake master cylinder to the frame, right below the rear brake pedal. The short side threads into the frame and the other side holds the master cyclinder on, but the one on my Fatboy was about twice as long.