From BMatthews reply:
In an otherwise properly aligned model with 2 or 3 degrees of downthrust already in place I would say that your balance point is too far forward.
In almost every case, an airplane that pitches up sharply with addition of power is nose heavy. It's hard to tell from the pictures, but it appears that the wing is set at a positive incidence angle. If that is the case, when balanced properly, it will require down elevator to trim at most any speed. The normal setup for that type of aircraft is zero incidence for both wing and tail.