The spark plug was whiteish
Good to hear things are running better. Idle problems and hesitation are some of the most annoying problems a vehicle can have. Your feedback validates the theory of a generally lean condition resulting mainly from the pilot jet and pilot jet passage aka pilot circuit (passage way).
A common mistake is that the pilot jet is just for idle or only in use until the carburetor "switches" to the main jet. In reality, the pilot jet never stops contributing gas but is overshadowed by the main jet the more the throttle is twisted. Even if the pilot jet is only supplying about 1/2 of the gas it should you probably won't notice any performance difference between 1/2 and full throttle however, the engine is running on the lean side which means hotter than it should.
The pilot jet clogs more easily than the main jet because it is much smaller and is more difficult to clean for the same reason. I have found the importance of the pilot is underestimated because it not only provides a stable idle, initial thrust but is a "ramp" to the main jet so you get steady predictable increases in power as you get into the main rather than a hesitation followed by an abrupt blast of power.
I recommend you review my carb videos and consider taking two courses of action:
1. order some larger pilot jets to compensate for the reduced gas flow.
2. consider drilling out the copper BB on for the pilot jet to directly access the passage with a tiny copper wire to properly clean the pilot jet passage - that is carb cleaning part III.
3. Also, pay attention to the section on testing the slide / diaphragm for vacuum leaks.
Carburetor Cleaning Part I
Carburetor Cleaning Part II
Carburetor Cleaning Part III
Kymco Carburetor Remove & Reinstall
