Scooter starts but wont stay on if i hold start button and give it gas it stays on once i release the start button it shuts off

SOURCE: 2007 kymco agility 125cc scooter

could be one of a few things. Most likely fuel related. 1) carb blocked main jet (whip it out n clean it) 2) air filter clogged up or split (remove spark plug and if it is black there is too much fuel and either the airfilter is blocked up or the choke is stuck on, if it is very white there is too much air getting infrom either a split air filter or leaking inlet pipe) 3) change spark plug.