I work on a lot of old Suzukis with shim-over-bucket valves.
They run very small valve clearances - .03 - .08mm, and the clearances tend to decrease over the miles. If you neglect this, the bike gets harder and harder to start and eventually will burn a valve.
Note that this is mm, not inches; one very common mistake is to mix up units; one thousandth of an inch is .025mm. So a .003" feeler is .076mm.
Anyway, one tool that is still surprisingly difficult to find is a decent quality set of metric feeler gauges that go down to .03mm (which is damn near foil-thin) and are NOT crapped up with inch approximations. Basically, metric only with no inch markings.
So anyway, one essential of any motorcycle garage where you work on stuff that revs is the tools and materials needed to check and set valve clearances. You can get everything you need for far less than the cost of paying a dealer, and you'll learn a lot.
Also, it's very difficult to find a dealer or shop that will actually perform a valve check properly without shirking large parts of doing a proper job; there are many, many tales of people who mark a few valve cover bolts, only to find that they haven't been touched.
Or they'll leave valves alone that are sitting at the bottom end of the spec. Valve clearances on most bikes tend to decrease over the miles, so it's good practice to go ahead and change out shims on tight valves in order to get the clearances into the upper part of the range.