a CR250 will not run 100 mph without some very serious modifications to the gearing. and even with those mods done, I don't think the engine could pull redline rpm in the top gear...
the top speed on a stock geared CR250 is only around 65-75 mph depending on altitude, humidity, barametric pressure, compression of cylinder, etc.
with a decent rider with good traction, it would accelerate from zero to about 60 in around 12-14 seconds.
unless you are referring to kph? which 100 kph would translate to about 62 mph...