I will admit that I'm not experienced with the B1250 throttle body procedure (glorified carburetor bodies) as I have not done mine yet as it will be a bit more tedious and procedurally involved, and for the monument with 1433 miles, idles and runs as smooth as an electric engine (no fooling). But I can tell you that I synchronized the carburetors on my 05 B1200, once after the first 300 miles and again one year later using the Morgan Carbtune (Awesome tool). Of the two sync procedures the first was the worst and needed considerable adjustment as it vibrated, the later adjustment only needed minor tweaking, OK smooth. This was also true for the mixture screws which were off on each carburetor by as much as a full turn between each one. While it is the rule rather then the exception that the factory will have the throttle bodies and carburetors well synchronized from the factory, a few of them come out maladjusted. So no matter what people will tell you to do in a PM, call and write Suzuki and insist on authorization to get the get the the unusual vibration as you describe (sunglasses rattling off) corrected under warranty and that you suspect synchronization but nevertheless something is defiantly wrong.