Every bike or car I have had performed better when it is cold.
The only difference is People 250 S. It runs much better when it is warm outside - 30-35 C is ideal!
This all depends on rejetting. When I had Kawasaki ZR-7S (750 cc), I had it rejetted with different main and pilot jets, another exhaust, K&N etc... there was a dedicated Web forum to this bike and we all used the same parts, yet the end result on dyno test was different in various parts of the world. It was the best on sea level and the worst for those who lived at higher altitude.
This is also the reason why some bikes work very smoothly when it is warm and have problems working when it is cold outside (and when they are just started). For example, my ex. Beverly 200 worked very smoothly when it was very cold, -10 - 0 C.
Bikes should be rejetted for different temperatures and altitudes, of course, nobody does that as it is too complicated, so I guess that factory setup is a compromise that should work under all conditions.
Kymcos are produced in China and you should check where exactly the factory is and where they are assembled and tested and probably they will work best under similar conditions. If you take them to 4000 m altitude or to very dry and hot climate, you will experience problems...
