Welcome Kymco Owners!
Nireen: Please read my two recent responses posted on your earlier thread under "valve adjustment", which address your top speed problem. Due to my advancing decrepitude I went to the wrong thread.
A compression test might reveal a slightly tired engine. With possibly no other faults - if belt and remainder of CVT is healthy snd correct. (weights, clutch, etc)Really need to run by your loss of top speed with your mechanic.Stig
My 2014 300i downtown maxes out at 155km/hr as indicated on the speedometer but probably like 140km/hr on gps