[Jeff McCune]

Unfortunately, motors aren't perfect nor identical. I assume you're having a problem along the lines of, "I drive both motors at 254, but the left side is moving faster."

This can be solved by using some constants at the top of your code and calibrating your drive train through experimentation. Try using the USER MODE on the OI to display the value being sent to one of the motors, and then tweak it until both sides are spinning the same. Then, take that offset and incorporate it into your drive subroutine.