Before you decide to adjust valves on your scooter, keep this in mind. If your scooter is fairly new, it's likely not your valves and perhaps a more simple fix. Be sure to check things like the fuel filter, fuel lines, vacuum lines, spark plug for spark, carburetor, and all wiring. I have seen cases where the coil wires have come a bit loose and caused a scooter to not get spark to the plug. Hey, it happens.
Anyway, before attempting to disassemble your engine, check for the obvious. You can only make yourself more familiar with your scooter by giving it a good look over.
If everything looks good but your scooter is running very poorly, check the valves to see if they need adjustment. Hope the video is helpful, and come back often for the latest videos!