ok, the top rotor has a mecanical gyro, not a flybar. it is what gives it stability, the faster you move forward the more it will fight backward.
and since you are pitching the heli with the tail it will counter act against that as well.
spin the blades up and tilt it, you will see the weight move out of plane(horizontal as in a hover).
the electronic gyro balances the rotor to each other to keep it straight. if you twich it in yaw you will here one motor try to speed up to counter this.
MORE over , need to move to a single rotor for more speed. a blade msr or sr 120 has the cobo of a flybar/mech gyro on the main blade for good stabilite but will move faster.. but it still fights it i forward flight.