49CC Scooter Idle slow to return after revving By rdh824 (Read 300 times)

[rdh824]

I just bought a 2018 Bintelli Sprint 49cc.  Did not run when I go it.  New Carburetor, intake manifold/Gasket.  Valves adjusted and starts right up. Scooter will idle fine and rev up quickly with no issues ,except when I rev the engine it stays high and takes a while to come back down.  Sometimes it will come back down sooner than other times.  Sometimes if I rev the engine again it will drop back down quickly. 

I have tried adjusting A/F, valve adjustment, vac hose inspection.   Engine is QMB139

[classacted]

when a moped runs out of fuel, just before the engine dies it will rev to high rpm's.

my first check for that symptom would be fuel supply.  all the way from the tank to the float bowl.

obviously, if the gas tank vent is plugged, fuel will not flow.

[rdh824]

Its got plenty of gas and this has been going on for a week now.  Bypassed gas suction valve and running straight to filter and into carb.  My only guess is the its the new carb?