Cook sweet potatoes in boiling salted water till tender, 30 to 40 minutes; drain and peel.
Cut sweet potatoes into 1-inch slices.
In a saucepan combine maple or maple-flavored syrup, brown sugar, butter, and salt.
Bring to boiling; simmer 5 minutes.
Place potatoes in 11x7 1/2 x11/2-inch baking pan.
Spoon syrup mixture over potato slices to coat.
Bake, uncovered, at 350° for 30 minutes, basting potatoes frequently.