an a 75 flh 4 speed baker be changed to belt drive and how?

 

you can put a belt drive on any bike. there cheap. either inclosed or exposed. check them out on ebay.

 

You talking primary or final ? Primary systems are easy and can be had around $300 for basic up to $600 for the full boat clutch and all , I like BDL systems they work and are plentiful .

Rear belt's can be done but take a lot of either late model parts and money or some skills and modifications along with money . Like cutting up the inner primary cover , starter housing , frame clearancing , swing arm mod's , ect

 

I put primary and secondary belt drives on my 1978 FLH about 15 years ago. It rode like a different bike, absolutely no vibration. I bought kit from Supermax, they are still in business and on internet. Also sent inner primary to him and he did machine work. It is not just a bolt on; it takes some work, however well worth it if you are going to keep the bike for along time.