What motor it is would help determin that but just measure from center to center of your intake studs...no need to take the intake off...Most are either 32mm or 40mm.
Oh well, I couldn't wait, it's 30mm (enter to center). And that's the 66/80cc china girl. I'm going to try to adapt up a 15mm rotary venturi Walbro clone. The spacing is exactly the same, so I'm turning the Walbro manifold into a spacer. Or I should say turned, I did it already, but now I need longer bolts, so it's on hold again.