hey man,
my 2 cents, if you have the time, skills, and a place and tools. i would go with the bobber, really love them. it will take a longer time to build a bobber than a cafe, i have built both and that is what i found, aswell as the cutting and welding that is included in it. this would all depend on the bike and type of build you are doing.
i might take my cb500 and bob it, next year.
any way, still prob with the carbs???
try taking the clamps all off and heat like von said, just keep the heat low just enough to make it warm.
any way, let me know how it turns out.
later.