Motorcycle Repair: Suzuki GT380 vacumn isssue, harley davidsons, vacuum leak

Question
I have re-built carbs hooked up vacumn line to petcock.
I have discoverd that I am getting no vacumn between carbs & petcock. I have bno blockages all new hoses. Bike will rrun in full prime postion but having trouble setting a consistent idle.  Why do I have no vacumn which would allow the petcock diaphram to opem

Answer
My specialty is on Harley Davidsons but I'll try to help you out. Most CV carburetors have a vacuum boot in the top of the carburetor  attached to the slide if this gets even the smallest of holes in it,like getting pinched when you put the cover back on after the rebuild it will allow a vacuum leak. If you can't figure it out you could as a last resort remove your petcock and replace it with a standard model that doesn't require vacuum to pass gas.