Sorry, but at that temp, a 4Lb bird is done in about 2 maybe 3 hours tops. Your therm is off, either that measuring the smoker temp, the meat, or both. Here is a popular Brine around here. Not overly salty and hasn't failed in 25 years...JJ
Juicy Smoke-tastic Chicken and Turkey
Here is a Brine and Rub that is a Favorite with members of my Family. I like Apple and/or Hickory with Chicken or Turkey. We determine doneness by measuring the Internal Temp (IT) in the thickest part of the Breast and Thigh, 165* and 175*F respectively. For a One Step Smoke with Crispy Skin the birds have to be smoked at a temp of 300-325°F. You can figure about 20-30 minutes per pound to reach the desired IT.
Families Favorite Brine
1/2C Kosher Salt
2T Gran. Garlic
2T Gran. Onion
2T Dry Thyme
2T Black Pepper
1C Vinegar (Any)
1-11/2Gal Cold Water to cover Chix
1/2C Brown Sugar, Optional
1T Red Pepper Flake Optional
Mix well and Soak the Bird over night or up to 24 Hours.
Remove the Chix, rinse if desired and pat dry with paper towels.
Place in an open container in the refrigerator overnight or up to 24 hours for the Skin to dry.
This will give a crispier skin when Smokng or Roasting...
Bubba Chix Rub
1/2C Raw Sugar
2T Paprika (I use Smoked if I'm just Grilling)
1T Chili Powder
1T Gran. Garlic
1T Gran. Onion
1tsp Black Pepper
1tsp Wht Pepper
1tsp Bell's Poultry Seasoning or Thyme
Mix well. You can put directly on the skin or mix with Butter, Oil or Bacon Grease and rub on and under the Skin.
Reduce the Chili Powder to 1 teaspoon if less heat is desired. Add 1T Kosher Salt if the bird is not Brined.