+1 on the carbs need to be synched . ITs very common for the 4 cylinder Wings to have the primary chain rattle if the carbs are out of adjustment .
You might get some insight on this subject from this link :Carb cleaning/sync'ing GL1100 - Steve Saunders Goldwing Forums
You might get some insight on this subject from this link :Carb cleaning/sync'ing GL1100 - Steve Saunders Goldwing Forums