Heat gas or charcoal grill. In shallow dish, mix oil, lime juice, chili powder and salt. Add chicken breasts, turning to coat.
Place chicken on grill. Cover grill; cook over medium heat about 12 minutes, turning once, until juice of chicken is clear when center of thickest part is cut (170°F). Remove from heat; slice crosswise into strips.
Meanwhile, in 2-quart saucepan, heat beans, salsa and cilantro over medium heat, stirring occasionally, until hot. Divide chicken evenly onto half of each tortilla; top with beans, cheese and sour cream. Fold tortilla in half over filling.