Hello, I used the search bar and still wasn't able to find a complete answer to my question so I'm posting it here. I have an 81 FXS with the stock dual disk front brakes. I believe the stock front master cylinder is 5/8 bore. I'm looking for an aftermarket one to clean up the bars a bit but the only ones that I can find are 14mm, which from what I understand is basically 9/16. Would I be able to safely switch from 5/8 to 9/16 bore. I also was looking into the sniper 2 brake lines as well. Would any of this work or would I have to stick to stock unless I switched over to single disk?

 

I have never changed MC on a bike so take this info for what it is worth. I did build a dual MC system with a bias adjustment for a car I built so I have some knowledge on this topic. Going from a 10/16 to a 9/16 MC will push less fluid at a higher pressure and lengthen your lever travel. Not sure how much you have to do calculations with lever pivot points and piston diameter. My guess would be it is fine. I have thought about doing something similar as my brake lever gives no feedback and has little travel.