Will these work on the front of a 91 FXR? I want to replace the old 2 piston caliper brake on the bike now. I just happen to have a front set of Harley 4 piston caliper brake assemblies that someone gave me after they upgraded to a set of chrome ones. The bummer is I need to buy pads for them

 

You didnt mention what the 4piston caliper was from? year/model.

 

Look up caliper adapter brackets by bikers choice for 00-up calipers to fit on 99 and down. That's what you will need