In a small mixing bowl, whisk together oil, syrup, vinegar, salt and pepper. Place chicken in a large resealable bag. Place thyme in the bag and pour in the marinade. Toss gently to coat. Allow chicken to marinate for at least 4 hours.
Remove chicken from bag and discard the thyme and used marinade.
Heat grill to medium heat and grill chicken until internal temperature reaches 165 degrees. Remove from grill and serve immediately.
It is fine for chicken to marinate 4-8 hours if the 4 hour time is not workable for your cooking schedule. The result with be a slightly sweeter chicken.