Scooter bogs at startup

Hello thank you again for let me join your site have a project scooter that I put together from a junkyard it was running fine everything was going good I upgraded it to the big bore 100cc!! But for some reason now when I started up it starts up backfires and then just bogs down right away I can’t get it to stay started for more than five seconds no matter if I put the Excelerator for five times before I started trying to hold it for throttle when I started it just bogged down right away any tips or help would be much appreciated

Sounds like your carb is not the right one for the motor.
Or your out of fuel... (we have all done it!)

Actually I just filled the tank up so there’s plenty of gas I don’t know the kind a carburetor I would need it it was a 50 mL scooter I just upgraded to the big bore kit hundred cc that’s it

You will need to run more fuel, richer. As the bigger cylinder needs more fuel.
Also try a new spark plug, it can be as simple as that.

Can I ask how do I run more fuel? Do I get bigger jets? How do I make it richer?

Yeah bigger jets