Ok, so I've meticulously restored this 72 Honda CB 350 and I can't get it to run right. I rebuilt the carbs as well as pretty much everything else, but when I start it, it revs way up without even touching the throttle. Before it started doing this, when you revved it up, it would be really slow to return to idle. It acts like a vacum leak but I can't find one. I balanced the carbs as best as I could. Any suggestions (short of throwing it off a cliff) would be greatly appreciated.