50
With a good rider and excellent road conditions the Yamaha YZF-R1 can do a 0-60mph time of about 2.5 seconds.
Over 140 MPH although I've never tried to push it all the way. I'm sure it would do 150 MPH.
fast
if it is a Yamaha wolverine 450 it will go 61mph
a Yamaha blaster can go around 75-80
very slow the rmz,yzf,kxf,sxfwill beat it easy
Stock straight off the line would prolly go 60-70 mph but if tuned it can go faster easily.
155mph
Not that fast but about 50 with no upgrades
the Yamaha ttr125 goes about 50 to 55 mph
about 70mph