I was given a 2001/2002 Honda CB500 twin (I believe it had over 80,000 miles on it - really worn piston and chamber; hence "old" to me). The carb was removed but the top had LPG injectors on the side and I was feeding it oxygen rich air (this was one of the controls set on 30% oxygen at 300 kelvins).
Or did you convert a Suzuki EX500 to FI?