It's called "Patina" or "Character". It shows that the bike has been ridden further than the nearest Dairy Queen.

Wipe it down with an oily cloth and ride.

 

Why not just paint these parts ?...b.

 

Ridden? It was half buried! LMAO!

 

The po only put 300 miles on this thing before he left it to to rott it was out there for a year just sinking in the dirt

 

On a previous bike I polished the forks, used process described above with several wet sands followed by several polish compounds in sequence. It takes time, and for the first while you will feel like you aren't seeing results, but when you get near the end when the mirror finish appears you will see it's worth it.

 

My fork legs used to look just like yours. The clearcoat breaks down and corrosion starts underneath. I used strips of Emory cloth. Sand the legs as if you are sanding the end of a copper pipe, before sweating a joint. You'll figure out the small tight areas.

Try Brasso metal POLISH on the trees. A buff ball or buff cone will help. Very good polish, very cheap too. I think I spent two hours on each leg, but it was worth it. They still look good two years later.

 

Harley's have had this problem since the 1980's when I bought my first new HD.
All my Honda dirt bikes that I've had, and my current 2008 Kawasaki KLR650 dual sport bike that really get abused and ridden in the salty sand and the swamp water over in Osceola National Forest don't get that corrosion on the fork lowers. All my Harley's that have conventional forks have gotten that corrosion. I think HD uses Japanese Showa forks, so why is it that only Harley's fork lower corrode? I noticed that the new Indians all have chrome fork lowers.