from my experience in racing pit bikes ive messured a tt-r 80cc to go around 100mph going up hill and flat road 140mph
i would say as a farm bike that it is in the low 80 km per hour
on a basic TTR-125, the top speed should be somewhere around 45-50 MPH
55mph
a stock ttr 125 goes 52 -55
45 to 50mp
150
120 mph
My 2012 ttr 110 can go 50-55mph
50-55mph stock
45mph tops
90 km/h
75 mph to 80 mph is the top speed of Yamaha ttr 250. This is true however you could increase or decrease your top speed by changing sprocket sizes, e.g A stock yamaha ttr250 with 14/44 gearing will reach approximately 140km/h or 87mph. Note i own a Yamaha TTR250 and have tested the bikes top speed.