I am pleasantly surprised that your bike is still running! These were prone to breaking down back in the day, as reported here on Chinariders when they were new, as well as a few years later when people were picking them up as used. The used ones were picked up from owners who apparently had them sitting around since they had moved 'up' to a bigger, name-brand bike. The problem was, we did not have a lot of people here on Chinariders who could diagnose the issues, and help each other find spare parts since Zongshen USA had folded up shop and left their HQ in Florida. For comparison, the Hawk 250 has become very popular around Chinariders, and people are fixing and repairing them thanks to the advice from other members.
Not sure if CSC could help you with engine parts, should you need them, but they are located in the greater metropolitan L.A. area of Azuza, and are the current US importer of Zongshen products. Besides them, many members have ordered parts directly from China via Taobao, so to put your mind at ease, your GS should be able to give you reliable performance for as long as you plan to own it!
What part of L.A. are you? My parents live in Northridge, and my sisters live in Granada Hills and Sherman Oaks. My in-laws live further north in Camarillo.
http://www.cscmotorcycles.com/