The proper spark plug gap for a 1999 Suzuki GSF 600 should be .024 to .028 inches. This may also be measured as .6 mm to .7 mm.
.07-.08
.030
0.7-0.8mm or 0.028-0.031in
0.6 to 0.7
0.7 - 0.8 mm (0.028 - 0.031 in)
part #: NGKDPR8EA-9
2006 Suzuki GSX600F Katana NGK CR9EK 0.6mm to 0.7mm .024 to .028 inches
.028"-.030"
The spark plug gap, on your 1994 Honda, is .013. Most spark plugs will come pre-gapped from the spark plug manufacturer.
Just a wild guess, but I would start at the top of the heads.......should see a spark plug wire connected to a plug........viola! spark plug.
0.031 to 0.035"
Under the bike on the left side is a 17mm nut.