sprite boolean "moving" is set: set x to sprite.x+dt*instancevarspeed
or if you don't want to use speed, but time taken to get from 485 to 1700, use
sprite boolean "moving" is set: set x to sprite.x+dt*(1700-485)/instancevartime
If you have a bullet behaviour applied and don't want the sprite to move with this, set the bullet speed to 0. Or if you only want the y-portion of the movement, set x to sprite.x-cos(bullet angle of motion)*dt*bullet speed additionally.
If you want it to stop at 1700, set
sprite x greater or equal 1700: set moving to false; set x to 1700