I would quite disagree with JJJ about his Kymco assessment. I have lived in Europe(Italy) for 8 years where scooters are extremely abundant and used for daily use by many people. There are a lot of Kymco bikes in Rome and according to my scooter mechanic at the Porta Portese in Rome, they are one of the most problem free scooters.............
Right or wrong - my take on this is that most problems on Kymco scooters (and probably all brands of scooters in the US) are caused by cold weather conditions during winters when the scooters are not used at all. Our local fuel does not get mixed with ethanol - but having read about ethanol’s properties I am quite convinced that ethanol is part and parcel of most scooter problems in the US - including Kymco problems.
It is no secret that even pure gasoline gets stale in fuel systems, and clogs up carburetors, fuel injectors, and fuel systems on any engine If the engine does not get used for a couple of months. A mixture of ethanol and gasoline in such conditions is a sure recipe for problems.
Adding to this - cold winters also takes it’s toll on batteries, specially when the batteries do not get charged regularly during winters.
Long story - but I think JJJ and his friends would probably have a very different experience if they found themselves in warmer areas during winters, used their scooters 365 days per year, and never used an ethanol / gasoline mixture.