Did you get your ped running yet?
While all the advice you received is good, lets first diagnose the concern before throwing parts at it and/or tearing the bike apart.
The easist way I know to identify a possible carb/fuel concern is by doing the following.
You need a can of eather, also know as starting fluid, but carb or brake cleaner in an spray can will do.
You stated that the bike starts, thats good.
Now, and this is tricky, just before the bike feels like it is going to die, or at the same time when you hit the accelerator, spray the "fuel source" into the carb.
It is a good idea to have the air box removed for this test.
If you can only keep the ped running by spraying the carb then the concern lies in fuel delivery!!!
This could be caused by a few things...
1.) mis-adjusted float
you have enough fuel to start the ped, but not enough to keep it running
2.) plugged meeting jet.
3.) restricted fuel flow. This could be from a plugged fuel valve, the one actually in the tank.
If you CANNOT keep the bike running by spraying into the carb, try spraying around the carb and intake.
Someone mentioned an air leak.
If you have an "air leak" you'll know where the leak is located because you'll be able to keep the ped running by spraying that area.
If you still cannot keep the ped running, then your next likley cause will be spark. This could be at the end, via the plug, at the beginning, points, or somewhere in between, coil or plug wire.
Hope this helps!