I think you have to start at the most common problems and work your way through. I have no idea what the guy is talking about as far as vacuum goes.
If it were me, I'd make sure that the wires are hooked up properly. You need to tell us things like how the kill switch wired up. Many members, including myself have spent hours figuring out that it was just a stupid wiring or switch problem.
The spark plugs that come with the kits are not the best and a spark plug can fail when under compression, you should try another one.
Are you giving it choke and 'tickling the carb" with that button on the left side of the carb? Is this a new kit? Need more info!