Hi Gabe and welcome to Ninjette!
Hmmm, 5-minutes is an odd number. Let's do some testing to get some data:
1. Run bike with gas-cap off. Does it run for more than 5-minutes?
2. Disconnect fuel-hose from carb-inlet and aim into measuring cup. Run bike for 30-seconds and stop. How much petrol did you collect in measuring cup?