Looks like you had to undo someone else's less than brilliant attempt to fix the carby. The plastic resin bodied Mikuni is tricky to fiddle with - especially for a noob. If you can pull one of these biatches down and get it to run you are on the path to enlightenment. Wait til you play with one that has 3 electric solenoids on it and a throttle sensor on it! You should be getting vacuum at idle and low rpm so my guess is you're checking vacuum from the wrong place. Is there a vacuum barb on top of one of the inlet manifold runners?