Just found this list online hope it helps, it came from NGK spark plugs
Spark Plug Part No. Stock No. Plug Gap Photo Iridium CR8EIX 4218 0.028
The 2004 Viper Yamaha spark plug gap is .018. Most spark plugs will be pre-gapped by the spark plug manufacturer.
The proper spark plug gap for a 1997 Yamaha YZF600 should be .028 inches. The best spark plugs to use in a YZF600 are copper.
The spark plug gap is .020 on your gapper gauge!
The proper spark plug gap for a 2002 Yamaha YZ250 is .024 inches. New spark plugs usually come pre-gapped, however.
The spark plug gap for a 1994 Yamaha YZ250 should be .024 inches. A Yamaha YZ250 is a 249cc motorcycle.
The recommended spark plug gap (per NGK) is .039"
.30 to .35
The 1998 model, Yamaha 250 hp outboard, requires an NGK BR9HS-10 spark plug, gapped to .039 in.
the gap is 0.024
between .28 - .31"
.032
.7-.8mm