This may be a dumb question byt here goes. Ok, Im building a bike from ground up starting with just a FXR frame. My question is What kind of motor can I use? For instance can I use the motor out of a Softtail? Will it fit/bolt in place? I want to go with an EVO and its an 84 frame.

 

For your FXR you need a rubber mount engine and transmission, with a swingarm mounted off the rear of the transmission. Softtails are solid mount and I doubt if they are interchangeable. Hopefully someone will drop by and clear that up!