In a small bowl, stir together maple syrup, Dijon mustard, soy sauce, thyme and garlic.
Make shallow cuts to both sides of the chicken.
Brush marinade over both sides of the chicken.
Place chicken on the barbecue with lid down. Turn and baste often with marinade for the first five minutes. Continue to barbecue until the chicken feels springy when pressed and a meat thermometer reaches 165F, about 5 to 7 more minutes, depending on your barbecue.