I don't have a meat thermometre so I rely on an TNT trick I've been doing for ages. Insert a skewer into the thickest part of the bird's thigh (but be careful not to hit the bone) and place a deep soon (lol, not slotted
) directly underneath of the spot where you placed the skewer into the chicken. If the juices run red, pink or even vaguely tinted rosy pink the chicken (this applies to turkey cooking too) is not done and needs at least another 15 minutes (or way more if the juices are red) more of cooking time. Repeat again after you've given it more time (make a new skewer hole) and see if the colour of th juices have changed. Ideally they should be anywhere from almost clear to a lovely golden colour.
I really should get a meat thermometre, and don't mean to imply that this method is better, just that it's a good way to double check that your bird has finished cooking.