CC, if they're anything like most automotive instruments, the bezels don't screw off. The bezel is tolerance fitted with a special tool and the only way really to get them off, so you can replace them again, is by taking them to a certified instrument repair shop. I've tried it and made a mess on my Harley, which has OEM gauges, but it is possible to do yourself if you don't mind a bit of a fiddle.
These are a couple of guys who have done it
http://recentabstract.com/vstarinstall/vstarinstall.htm
http://laudeman.com/bug_speedo.html
It's made like this so no-one can tamper with the mileage etc.
Mick
