Okay, i learn something every day, If you look at the carb mounting on my Tuber Buell, or some of my sportsters,
while the carbs are mated to the engine with a Rubber boot or coupler, the carb itself is supported and held firm by the thru bolts in the aircleaners to the cyl heads, so the carb CANNOT pop off.
once in a great while,,often when my choke is on or the engine loads up and being lugged and THEN accelerated
I get a hiccup or cough sometimes with my 86 sporty, I know I dont have the S&S tuned quite right, and will be addressing that... my other carbed bikes dont do that. Id say you have a tuning issue going on if you are having that problem.
Now, most of other bikes are vintage British and a few Asian bikes, I LOVE using round slide Mikuni VM carbs, they work well for me, great tuneability, very flexible and best of all, they just work really well.
But if you look at their typical mountings, they use a very similar boot to this Buell blast system, and often people just mount the carb to this boot and let it hang there unsupported, It works well for a while but you will see cracking and deterioration of the rubber boot, Now, mikuni carbs have on the carb body a small U shaped hook, that is intended for a support. Some use thick O rings off a bracket, some use rubber strap, some use a hard alloy or steel bracket hooked into that U shaped hook and that supports the carb and takes the weight off the coupler,.
Now i never have worked on a Buell Blast myself,, but examining these pictures it sure seems to me that whats needed is some sort of support or brace or suspension for the carb body. Doesnt look like it would be easy to make one thats for sure,
Now lastly, a word about those couplings,,,, some are not true rubber, they can be a composite or Viton, or any number of materials, Some flat track and road racers use a commercial grade sandblast hose for custom length intakes for example, (IE Triumph, BSA, Norton, Yamaha XS650/750 for example) But NEVER use a petroleum product on them such as grease or petroleum jelly, intead use Dish soap when mating together to ease in.
May asian bikes such as CB750s or other inline 4s have rubber boots that harden up, and its really tough to slide the carb racks back in place and tighten the clamps, Use dish soap liquid like Dove or palm olive,
Now, if you have access to industrial suppliers, an excellent product is out there for O ring sealants and lubricants, I used to work in aerospace foundry and we had vacuum chambers and high pressure gas and air fittings and when sealing those up with boots or Orings we used a commercial grade O ring lubricant and sealer specifically for joints like that, Permatex, and 3m come to mind, but theres others. Im too lazy to go to my shop and look in my box of sealers and chemicals, These products are made FOR high heat and chemical exposure applications. We used them in a foundry for Stainless and Titanium casting apps. Not a bad thing to have in you toolbox. just my $0.02