Arduino bluetoth car

/*
  Bluetooth car

  written by sanuka 

  rx------->D1
  tx------->D0
  vcc------>+5v
  GND------>GND
*/
#include <AFMotor.h>  //include the library

AF_DCMotor motor1(1); // naming the motors
AF_DCMotor motor2(2);
AF_DCMotor motor3(3);
AF_DCMotor motor4(4);

char val;
void setup() {

  motor1.setSpeed(255);  //give a speed to the motors
  motor2.setSpeed(255);
  motor3.setSpeed(255);
  motor4.setSpeed(255);
  pinMode(13, OUTPUT);

  Serial.begin(9600);

}

void loop() {
  if (Serial.available()) {
    val = Serial.read();
    Serial.println(val);
  }
  if (val == 'F') {
    motor1.run(FORWARD);
    motor2.run(FORWARD);
    motor3.run(FORWARD);//go forward
    motor4.run(FORWARD);
  }
  else if (val == 'B') {
    motor1.run(BACKWARD);
    motor2.run(BACKWARD);
    motor3.run(BACKWARD);//go backward
    motor4.run(BACKWARD);
  }
  else if (val == 'R') {
    motor1.run(FORWARD);
    motor2.run(FORWARD);//go right
    motor3.run(BACKWARD);
    motor4.run(BACKWARD);
  }
  else if (val == 'L') {
    motor1.run(BACKWARD);
    motor2.run(BACKWARD);
    motor3.run(FORWARD);//go left
    motor4.run(FORWARD);
  }
  else if (val == 'S') {
    motor1.run(RELEASE);
    motor2.run(RELEASE);
    motor3.run(RELEASE);//stop
    motor4.run(RELEASE);
  }
  else if (val == '5') {
    motor1.setSpeed(150);
    motor2.setSpeed(150);//change speed
    motor3.setSpeed(150);
    motor4.setSpeed(150);
  }
  else if (val == 'q') {
    motor1.setSpeed(255);
    motor2.setSpeed(255);
    motor3.setSpeed(255);
    motor4.setSpeed(255);
  }
  else if (val == 'V') {
    digitalWrite(13, HIGH);
  }
  else if (val == 'v') {
    digitalWrite(13, LOW);
  }
  delay(100);
}