If your dirt bike is 90cc how much mph does it go?

If your dirt bike is 90cc how much mph does it go?
Well a 90cc thumpstar goes about 85km/h so how many kilometres in a mile is about 1.6 so 1.6 x 85 = roughly 77mph

I've also got a 90cc Thumpstar and I got it up to 72km/h on a dirt track so I could probably get it up to 85-90km/h on ashpelt.