I have a yz 80 2001 small wheel and does about 75 mph
Most the time that means it needs a front end allignment. Possible bad front tire or wheel.
could be bad alignment
Probably wheel balance.
inner tie rods bad at rack and pinion
I'm not surprised. Go to the alignment shop and get a wheel alignment. It will cost about $80 US. Unless you damaged some of the steering components. It's your ONLY option.
80 mph = 128.748 kmph
80 mph = 128.7 kph
80 mph = 69.5 knots
Mach 80 = 60,896.6 mph
80 mph = 128.75 kph