FYI, CBR600 (I think most years) and 599 gas caps are all interchangeable. I wouldn't doubt that other bikes from Honda all fit, too. RC51, 929, etc. They seem to all look the same to me and use the same 3-bolt layout.
2009 Aprilia Tuono - Ginger
2001 XR650R BRP (Big Red Pig)
2006 Honda 599 - Ex wrecked it :-D
2007 Honda CB900F (sold)
2006 Honda VTX 1300C (sold) YouTube Channel