In a large bowl, mix flour and salt; cut in shortening until crumbly. Gradually add water, tossing with a fork until dough holds together when pressed. Shape into a disk; wrap and refrigerate 1 hour or overnight., Preheat oven to 425°. In a large bowl, toss pears with lemon juice. In a small bowl, mix flour, 1/2 cup sugar and cinnamon; add to pear mixture and toss to coat., On a lightly floured surface, roll half of dough into an 1/8-in.-thick circle; transfer to a 9-in. pie plate. Trim crust even with rim. Add filling; dot with butter., Roll remaining dough to a 1/8-in.-thick circle. Place over filling. Trim, seal and flute edges. Cut slits in top. Sprinkle with remaining sugar. Bake until crust is golden brown and filling is bubbly, 45-50 minutes. Cover edges loosely with foil during the last 20 minutes if needed to prevent overbrowning. Remove foil. Cool on a wire rack.