I remember doing that in the 80s on some of the new Honda scooters. Talk about easy it took longer to remove the plastic covers than to adjust the valves. When the Motocross guys who were used to 2 strokes starting getting 4 strokes with the valve adj. process and saw that external adjustment on those scooters they were pissed at Honda big time. Then again Honda had those 4 strokes singles XR/XL 650 that had 2 rocker arms per valve from the 4V"Radial" head design that had a 5th valve for decompression system at the same time. Leave it to Honda to make a scooter system so easy and a dirt bike so complex. At least with the NC bikes the Auto & Moto engineers worked together.