I know this is an older post but I wanted to say I had this problem today. For me it was my my front motor mounts bolts worked loose

 

There is another possibility. I had a 93 FXDL that I rode for 74000 miles so I know a bit about the early DYNAs. One mistake I made when I first started riding it was that I was using the rear brake too hard in relation to how hard I pulled the front brake. You said your problem happens in deceleration but, I'm not sure if you mean with or without braking. Anyway, on the early frames the starter is only about 7/16in away from the rear down tubes of your frame running between your swingarm and rear tire. Remember that the motor, swingarm and the rest of your drive train are separate from the rest of your bike and are only connected by the isolator-motor mounts and top motor mount. What happens (and it is worse if the motor mounts are worn) is when you use too much rear brake and not enough front, the whole drive train pulls back inside the rest of your frame causing the starter to hit the rear down tubes running through your swingarm. I realized this and started using more front brake (as I should have been doing because that is where the real braking happens), this improved it a lot. I guess I had some misconception about braking with the rear more as a safety gremlin in the back of my mind. Even after changing the motor mounts you can make the starter hit the frame, and if you try to pull a hole-shot w/out enough rpms to break the tire free quickly you'll find you've dented the exhaust shield on your front exhaust as the drive train slams forward into your front down tubes. Also on the early 92, 93, and 94s I believe the angle of the cross member where the front motor mount attaches was different and got changed when they changed the frame in 95 with the pan section for the seat to lower it. I also zip-tied a piece of 1/4 black fuel line around the down tube where the starter would hit it. You will be able to see where they have been hitting each other if you look. So keep this in mind if all the other handle bar bushing and motor mount replacements don't totally solve the problem. Good thing the dual disk front breaks are awesome on the early DYNAs. Also, if it seems like you never have to replace the front brake pads, you are not using the front brakes hard enough. I don't know how seasoned a rider you are so please don't feel offended if it seems like I'm saying you aren't braking correctly. Good luck and don't hesitate to ask me about other early DYNA issues like how they had to redesign the clutch basket for 1994 as the original ones failed causing a horrendous scraping in the primary on the 92 and 93s. It's an awesome bike so enjoy.
Bill