How to switch a electric scooter to a gas?

I have x-treme x250 electric scooter... I want to put a gas engine on to go faster! No welding!!! I need a gas engine for it so if you know were to get it post the link! It can go faster than lk 25 mph but it has to go at least 15. If it helps i live in indianapolis indiana... I have tools but no welders and stuff.. I need a direction manual basically but dont make it hard to understand.. If you answer i would love it!!!!