Preheat barbecue to medium-high. Blend orange juice with maple syrup, mustard and rosemary.
Brush roast with oil and sprinkle evenly with salt and pepper. Sear pork on the grill for 2 min. per side or until browned. Reduce grill heat to medium.
Cook, with lid closed, turning and basting roast often with juice mixture, for 35 to 40 min., or until the internal temperature reaches 155°F (68°C) on an instant-read thermometer. (Don’t overcook as roast can dry out.) Tent the roast with foil and rest for 5 min. before slicing. The roast will continue to cook as it rests, coming up to 160°F (71°C).