How to set rotation of z to a particular value and then apply torque about another axis ?

I am trying to set the EulerAngle.z to a particular value and then add flip functionality about X axis...

example :

  transform.eulerAngles = new Vector3(transform.rotation.eulerAngles.x, transform.rotation.eulerAngles.y, zValue);
 
 rb.AddRelativeTorque(Vector3.right * flipAxis* flipForce);

Currently the bike would rotate arond the X axis till 90 and then the bike would just invert instantly.