I'm pretty sure there aren't any vacuum tubes going to the air filter only the crankcase breather. Trace the tubing it should go to the top of the rear cylinder. I rerouted mine to a breather under the bike cause I didn't want oil in the carb. Then, I just plugged the hole on the housing.
Yes I believe you are right. Some times my brain farts are really huge. That's what happens when you get past 67 years old. I need to apologize to Major M.and I do.One should engage brain sometimes.