Make sure the reservoir is leveled; move the bike/handlebars around until it's as level as possible before you change fluid levels. Ideal fluid levels should be even with the bevel. Sometimes utilizing sloped ground/driveways helps a lot. Just be careful your bike doesn't start rolling away while on the jiffy stand. I believe newer bikes use DOT 4 and mid 2000's bikes use DOT 5 (purple when fresh).

 

Im not the OP. But I solved my reservoir leak issue.

I took off the top. Removed just a little fluid. Cleaned the cap and the gasket really well and just snugged the two screws when putting it back together.

Then I went on a 100 mile ride with a buddy. Keeping an eye on the master cylinder and no leaks. Problem solved.

 

Cool, glad you got it worked out. I'll have to try that and see if it solves my problem as well.

 

I ran into this last year when I put my apes on. Seems to be a 'known issue'. One you open the cap, it most likely will leak. There have been revised gaskets, torque specs etc. After fiddling with it on mine for about 2 months, I bought a chrome Drag Specialties cap and gasket. Best 20 bucks ever spent on the sporty.

Take a walk through the used bike department at your local dealer and check the caps. You'll be surprised how many have paint peeling from the m/c's, and not just sportsters.