Here is an intake manifold for 250cc GY6 engines
The CN250, CF250, CH250, and what is commonly known as the GY6 250 are all variations of the Honda clone 244cc engine
30 Day Warranty Description

Here is an intake manifold for 250cc GY6 engines. The CN250, CF250, CH250, and what is commonly known as the GY6 250 are all variations of the Honda clone 244cc engine. They are all vertical cylinder designs with variations occurring in the CVT area. The component engine parts are usually interchangeable between all models.
First designed for the Honda Helix, this ubiquitous intake manifold fits the Honda Elite 250, as well as numerous CF Moto 250cc, Roketa 250cc, SUNL 250cc, Tank 250cc, and many, many other scooter models with the 250cc GY6 engine. If you have a nominal 250cc Chinese-made scooter, then this manifold will probably fit. In addition, this same manifold can be found on various go-kart and ATV than are powered by the 250cc GY6 engine.
In some literature, this intake manifold may be referred to as a “carburetor insulator interface.” Specifications

Bolt Hole Spacing: 56 mm
Inner Diameter (carb side): 33 mm
Inner Diameter (cylinder head side): 27.5 mm