Quote from yoyoML :

You got the effect in reverse. Steering in one way rolls you in the other.

Suppose you're traveling forward, so the front wheel's angular momentum points left. You "steer" to the left by exerting a torque, whose direction points up. The change in the wheel's angular momentum is then in the direction of the torque, which is up. The originally left pointing angular momentum then points left-up, rolling you to the right.

Steer (yaw) left -> roll right. One more reason to countersteer.

Suppose your bike begins to fall to one side: rolls left. The torque that the bike exerts on the wheel points aft. The left pointing angular momentum then points left-aft, yawing the wheel to the left.

Roll left -> yaw left.

You see, that the gyro is "stable" arises from this alternating force and response: yaw left->roll right->yaw right->roll left.... If you had "yaw left->roll left" like you said, then the gyro goes yaw left->roll left->yaw left even more->roll left even more... until it diverges.

Yes, you're right of course. I got it backwards. Thanks for catching it.

Shotglass, ignore what I said on this one.