Issue trying to rotate an object in X axis

Hello,

I have an issue trying to rotate an object in X axis, the object only rotate 0 to 90 degrees an then stop.
This only happens in X axis, I have no problems with Y and Z axis.

    float speed =  1f;
    Vector3 rot;

    rot = transform.localRotation.eulerAngles;
    transform.localRotation = Quaternion.Euler(new Vector3(rot.x + speed, rot.y, rot.z));

Version 2017.2.2p3

Thanks

Try this

float speed = 1f;
transform.Rotate(Vector3.right, speed, Space.Self);