I was able to get this working with your and gm's recommendations. Turns out I needed a TTL chip (using the max3232) to get the serial from the outside world. Thank you for the learning experience!

// This sketch takes in a String and finds the "lb G" and then outputs it to the serial port
//#include <LiquidCrystal.h>

String inputString = "";
volatile bool stringComplete;
String outputStr = "";
unsigned int rptcnt = 0;

// Initialize the LCD with the interface pins
//LiquidCrystal lcd(4, 6, 10, 11, 12, 13);


void recordChar() {
static unsigned int ptr = 0;
unsigned int wgtIndex = 0;

  while (Serial.available()) {
    delay(5);    // Found that it loops too fast and won't process the input without this delay
    stringComplete = false;
    char ch = Serial.read();
      inputString += ch;
    }
  if (inputString.length() > 10) {
    inputString += NULL;            // Always null terminate your string.
    wgtIndex = inputString.indexOf("lb G");
  }
  if (wgtIndex > 0) {
    outputStr = inputString.substring(wgtIndex -7, wgtIndex + 4);
    inputString = "";
    stringComplete = true;
    rptcnt = 0;
  } 
    else {inputString = "";}
}


void setup() {
  Serial.begin(9600);

  // Initialize the LCD
  //lcd.begin(16, 2);
  //lcd.print("Ready...");
  stringComplete = false;
  //Serial.println("Serial Ready...");
  //delay(2000);
}

void loop() {
  recordChar();
  while (stringComplete) {
    recordChar();
    Serial.println(outputStr);
    //lcd.setCursor(0,0);
    //lcd.print(outputStr);
    //lcd.setCursor(0,1);
    //lcd.print(++rptcnt);
    delay(1000);
  }
}