Go with the 350. depends on your budget, 305 should go pretty good
Torque specs for what part of the engine? standard answer: keep turning until it gets easy...
120-130hp
You may find at least the peak torque and some other info at the Wikipedia weblink below. It is not the torque curve but it is a start.
there is no such bike yz490 didn't start till 1982 and went on to 1990 before this it was a 465 ....
if your wanting to change the head the torque settings are as follows: Cylinder Head_______(1.8-2.0kg-m)[13.0-14.5ft-lb] FlyWheel___________(2.6-3.2kg-m)[18.8-23.1ft-lb]
Depends on the engine
tire psi
Quoted at 95hp @9000rpm.
about 12 hp
17
50:1
82.00 HP (59.9 kW)) @ 9000 RPM