since i replaced my pads i have no problem just pressing on the pedal a little and having the back lock up like any other machine out there..

 

My 00 sportsman has the original pads in the back and I can lock them up on dry tar. The same with my 05 scrambler. May be the rotors? Like cars, if the rotors are bad the brakes don't work as well.

 

Same problem on my '97 Scrambler. If I stomp it hard enough it'll slow, but nothing significant.

 

The rear brakes were originally designed as a backup to the main system (main brake lever already puts pressure on the front and rear brakes) and has a small master cylinder that doesn't have a whole lot of stopping power compared to the old mechanical rear brakes of the 90's. Just make sure the pads are in good shape and every now and then use the rear brakes to keep the seals in the small master cylinder from getting dry and sucking air. OPT

 

Did they improve the brakes at some point? I have no problem locking up the rear wheels with the foot brake on my 2008 Scrambler.