Top speed is not what a dirt bike is all about, it is how quick they are. With the broad range of displacement (cc's) and the 2 and 4 stroke engines, there really isn't a good answer to this question. I have a 2 stroke 200cc and a 4 stroke 525. The 200 will top out around 65 while the 525 somewhere around 95, yet in the woods, the 200 is quicker.
not that fast
Not as fast as i am!
Yz250
fast enough
fast
A 70cc dirt bike will achieve a top speed of around 40mph
very fast no it bout 130
it can reach a speed of 90mph its fast!
Define normal dirt
it all dipends on the bike
no not at all
about 40mph