A friend of mine has a nice Vespa Primavera ("Sears" VMA1) that has been sitting for awhile after being restored. It would start, but would not idle properly. So he brought it over to the garage for a little fiddling...
When it got to me, it would start and idle, but would not rev out properly, and seemed to bog when I got on the throttle. All points lead to the carburator.
Luckily on the smallframes, the carb is pretty accessible. I tried to fiddle with it without taking it off, to see if that would have any effect. No such luck! So time to pull the carb.
The easiest way to do that is to remove the gas tank. So here, you see me loosening the manifold clamp to get the carb loose. Once it was off, I cleaned it thoroughly. With a cleaning, and a bit of adjustment, it ran fine. Easy fix!