The nx 76 is .46 cubic inches. That's 7.537647 cm cubed. That means is would have to be .47 cubic inches to make 7.701509 cc. Now I want to know, was I lied to, or is my math wrong.

I think that maybe the .46 is rounded down a bit. It might be like .46666 or something. Each of the sizes is in the ballpark, so I'm pretty sure it's just rounding. All engine sizes are rounded. I don't think any engine size is exactly .28 or .15. But anyway...