Place the maple syrup and the butter in a small saucepan over medium low heat. Bring to a simmer and then remove.
Bruise the rosemary with the back of your knife and place it into the maple butter sauce.
All this mixture to cool to room temperature.
Stuff each chicken cavity with 4 lemon halves, half of the rosemary and half fo the thyme sprigs.
Truss chickens with butchers twine.
Mount the chickens to the bbq rotisserie spit and secure in place in the center of the rod so that they will cook over the middle grate of the barbecue when the rod is in place.
Drizzle the meat with olive oil and season liberally with salt and pepper.
Remove the rosemary sprigs from the cool butter sauce and set ½ cup (125ml) aside for basting the chicken. Fill the barbeque injector with the remaining sauce and inject the maple rosemary butter into the thickest parts of the bird until it is plump and juicy.
Prepare barbeque for indirect rotisserie cooking by keeping the middle burner off and leaving the 2 side burners on medium heat 350°F (160°C). Place a drip pan on the center grill. Mount the rotisserie being sure that the chickens rotate over the middle grate where the drip pan will catch any run off juices.
Close lid and cook the chicken for 1 ½ – 2 hours basting with the reserved maple rosemary sauce and any pan drippings every 20 minutes. Chicken is cooked when a thermometer inserted in the thickest part of the meat reads 160°F (71°C). Be sure that the thermometer is not touching the bone or the reading will be inaccurate.
Remove the chickens from grill and cover in tin foil for 15 minutes before carving.