This intake manifold is most commonly (but most exclusively) used for GY6 Engines, most commonly for CF Moto and similar brand machines. This engine is most commonly used gas scooters, as well as dirt bikes, ATVs and buggies / go karts etc. Manifold opening is 28mm, breather side opening is 34.7mm an the mounting holes are 5.6cm apart center to center.
Manifold Inner Diameter: 26.6mm
Mounting Holes (center to center): 55.4mm
Breather Inner Diameter: 33.2mm
Breather Outer Diameter: 46.9mm