Thanks a million, Eric, for taking time looking at our bikes and trying to find a solution to the puzzle. The "enriching the mixture" prescription may just be the silver bullet we've been looking for. Hopefully we can find someone soon who has access to the Jialing diagnostic instruments and is capable of tuning the ECU system through the instruments. Such a diagnostic setup is not currently available in Shanghai, unfortunately.
Again, many thanks, Eric. The coffee was excellent and the highly functional workshop in your garage is the world's tidiest.
Cheers!