Another impossible dyno chart. Not saying there is anything wrong with the build or even the numbers.
HP and torque are unit measurements of work. There is no such thing as unwork. You cannot do negative work, it does not exist (although my lazy sister comes close). You can do no work, a little work, a lot of work or anything in between, but you cannot do unwork.
Even if the bike had a reverse gear that would not be negative work.
Definition of torque;
1: a force that produces or tends to produce rotation or torsion <an automobile engine delivers torque to the drive shaft>; also : a measure of the effectiveness of such a force that consists of the product of the force and the perpendicular distance from the line of action of the force to the axis of rotation
2: a turning or twisting force
Definition of HP;
1: the power that a horse exerts in pulling
2: a unit of power equal in the United States to 746 watts and nearly equivalent to the English gravitational unit of the same name that equals 550 foot-pounds of work per second
3: effective power <intellectual horsepower> <computing horsepower>
Notice that neither definition specifies direction. Therefore going the opposite direction is just HP or torque in the other direction.
Just like MPH, you can go 20 MPH forward or backward or West or East, or even up or down, but you cannot go -20 MPH. There is no such thing.
Rant over...return to you normally scheduled thread....