Gearing changes CYCLONE

here is my NEW in crate purchase . It is a 250 cc engine . I do not know what kind of copy - cat engine the Chinese have used to build this bike ,Its a pretty cool bike - 5 speed , clutch ,etc . PROBLEM is with the current gearing it will top out at 42 mph ,great i the dirt , but not so good for a dual purpose bike .
Attachment 18684
I need to identify the copy cat engine and get a larger counter shaft ( front) sprocket and or a smaller rear gear .
Help would be appreciated !

What? Top out w/ 42mph maybe ??? in carb. Checked choke's position?

I am a mechanic - the Cyclone is running fine - it is turning 7500 rpm at 42 mph.

So high rpm on just that speed? What sprocket / rear gear combi in on there???

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Wheels are 16"?

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Front sprocket 15 tooth . rear is 35 tooth and the tires are 12 inches has , the distance from bolt holes across the hub is 77 mm