I have an 08 sportster, 4900 miles on it. Back break randomly went out the other day after riding. I rode for about an hour, got home shut the bike off started it again and when I did there was no pressure to back break. Also when I press pedal the light doesn't even come on. I looked in manual for a possible fuse issue but could find a fuse to back break if there is one. Any one have any ideas? Thanks guys

 

Have you checked the rear brake reservoir for fluid?
No fuse is going to cause the symptoms you describe.
You can test the brake light by using the front brake lever.

 

Brake light works when front brake is engaged. I have check fluid levels they are fine. My only thought was maybe master cylinder went bad, but with only 4900 miles it shouldn't be bad. So wasn't sure.

 

Bleed the brakes first. Regardless of miles, age of the fluid could be playing a factor.
If bleeding doesn't help, rebuilding either the rear caliper or master cylinder would be next.

 

Brake line could be old too. Check the date code on it since you'll be working on the brake anyways.

 

Master going bad = visible leak.

 

is the linkage connected?

 

The pedal would flop if the linkage was disconnected.
There's a kit for the MC rebuild. Part # 42810-04B, for my '05. Verify for your '08, but I believe it's the same #. The procedure isn't too difficult. I remember that having a bench vise, makes it easier. Instructions come with the kit.

 

Not always. The diaphragm in the rear master has been known to tear and the result does not produce a leak, it just doesn't build pressure. These "rubber" parts can age out with time, not just mileage. The rebuild kits are fairly inexpensive.

 

Your rear brakelight switch may have failed, mine did. Fairly inexpensive DIY fix.

John