I always try another CDI if I find no spark. There are other reasons a spark may not happen as well. Try to get a spark before seeing if you don't have gas, because you already know there's no spark and gas does not ignite without it.
Common causes for no spark:
-No power from stator to CDI
-No power from CDI to ignition coil
-No power or bad connect between coil head and boot (maybe loose wire?)
-No power from boot to spark plug or loose connection
-Bad or wrong spark plug
If you check the stator wires with a multimeter and see there is power (AC) from them, then you move onto the CDI since this is the next spot the power goes from the stator.
Then check if the CDI is okay (no easy way to test it besides using another known working CDI from a buddy or your parts bin).
If it still doesn't fire with a known working CDI then move onto the ignition coil. You can connect a wire from the green terminal on the ignition coil to the frame for extra grounding, use something thick, I use 12 gauge. Unscrew the wire from the coil and the boot, and cut about a quarter to a half inch off each end, then screw them back on and connect it back up to the wires and the spark plug. If that doesn't work try another known working coil.
Try another spark plug, NGK is the most used brand in scooters because of it's reliability.
If you STILL don't have a spark, then throw the scooter out a window.
As far as the electric starter goes, it's easy to rewire it and make it work, but let's get you sparking first.
