If you have your gyro set to heading hold, it may be that your tail rotor is at full lock before you start increasing the throttle. The tail servo will not recenter when in HH mode; it just sits at the last position it was in before yaw movement stopped. So....if you swing the tail around when carrying the heli to the launch pad, the gyro may go to full lock in an effort to compensate, and just stay there after you set the heli down. Once the tail rotor gains enough speed to create authoritative thrust, it will want to swing the heli around until the gyro catches up and stops it. Bottom line, check Phil's suggestions too, and ultimately, you will find yourself getting used to feeding in rudder as the rotor is spooling up to keep the heli straight. The gyro is not very effective at locking the tail until the heli is up to speed and off the ground.

Re the reverse switch: The servo reverse function on your radio will control which way the transmitter tells the servo to go based upon stick input. The reverse switch on the gyro controls which way the gyro tells the servo to go based upon yaw movement. They are totally separate functions and one does ont inflluence the other. Here's how to check each:

1. Move the stick to the left and check to see whether the tail blade pitch increases or decreases. Note which way the tail rotor spins and whether the stick movement will create the desired thrust direction to move the NOSE in the direction of the stick. If not, use the servo reverse function on your transmitter to change it.

2. Center the tail rotor servo and watch what it does when you move the tail of the heli to the left (nose to the right). It should move in the same direction as it does when you move the stick to the left. If not, flip the reverse switch on the gyro.