Need help, I have a viking 50cc 2 stroke bike and it runs great at idle and runs a little at WOT, then it acts like it's out of gas and stalls. I've checked everything except electrical problems, but the funny thing is, if i open up the drain on the bottom it starts back up? The carb was clean the float appeared to be in the proper position. checked plug gap (plug looked nice) it was .020 so i moved it to .030. like i said the bike will idle, but if you ride it a little bit it loses power and then dies. I'm baffled. btw the motor is a 50cc motor by scooter maker QINGQI.

 

in case anyone else is interested,I think wehave the problem narrowed down to the bowl vent.