I just purchased my first HD. 1975 sportster. Its been neglected, but the price was right.
I noticed a few interesting things about it.....
It has had the dual plug mod done, or swapped heads, not sure.
s&s carb and breather.
had dual rotors and calipers, no brake line on the left side.
It does not have the original tank, I was told it was a fat bob tank, has two filler caps and what used to be an instrument cluster (speedo?) with ignition switch.

Main thing i'm curious about is the front brakes. Was this a common mod? And how do I go about identifying the calipers?

Any help would be appreciated.

 

take a couple of pictures and post them the guys will ID what you have good luck with it - the OEM parts book and service books will have to happen as you need the correct terms to ask questions

 

Service manual is part number 99484-78. Parts catalog 99451-78B. Definitely need pics of the heads, both sides.

Sounds like 1978-on front end but need the pics, including the master cylinder.

 

Welcome aboard.