Things may be different than years ago but on motorcycles the valves had to be adjusted after the eng had not been run for awhile & the parts had returned to their former dimensions. Parts expand when hot & return to a different size when cooled off. This was on motorcycles but it only makes sense that it would be the same on scooters. An engine is an engine regardless of what it is in!
Irish
P.S. A metric to inches conversion can be found on the web. I don't have the web# offhand but it has helped me immensely!