My Star Twin is now fitted with a 276 carb as I had no luck with the twin carbs. However I did have a fire as the engine back-fired after I had flooded the carb to start .
Since then I have fitted a gauze from a tea strainer and secured around the carb mouth with a hose clip, not pretty but prevents a fire. At Kempton park in Dec a guy was selling gauze filters for a £1 each that could esily be modified.