Using a small paring knife, run through the center of the onion. Cut out a space large enough to fit the rotisserie rod. Slide rod into onion and through turkey. Secure forks, but not tightly yet. Place onto motor achieving a good balance of the bird. Secure forks completely. Cook turkey for 3 1/2-4 hours or until the thigh and leg meat reaches 185 degrees F. Check several spots for the correct temperature before removing. Baste turkey after the first hour and do so until 30 minutes before the turkey comes off the grill.