GOOFIT Carburetor with Accelerator Pump for 4 Stroke GY6 49cc 50cc Engine ATV Scooter #78 main jet, #34 idle jet,come with electric choke ,accelerator pump and oil drain pipe Manifold intake:18mm,the outside diameter connected with air filter:40mm Fit for 4 stroke GY6 49cc 50cc engine Accelerator pump helps to enrich the air fuel mixture at the time of an initial throttle change to help make a smooth transition from idle to acceleration by adding a small amount of fuel while still at low rpm and slight throttle opening. Arrival within 1-2 days (Sold by GOOFIT and Fulfilled by Amazon),Arrival within 7-15 days (Ships from and sold by GOOFIT)