There should be plenty of advices out there. I went to Jia Jie's favourite general servicing at Autopoint in Ang Mo Kio.
The old uncle whom serviced my bike seemed knowledgable, that's why Jia Jie trusted him. Since I ride my bike occasionally, the uncle recommended to put semi-synthetic oil rather than fully-synthetic oil. Although it isn't really good, but it should fit my style of riding. If I decide to ride more than 60% a week, I should change it back to fully-synthetic oil.
After weeks of riding, I realised my SYM GTS 200 jerks when riding off 10-20 KM/Hr around 3-4K rpm in the morning after starting up. Having check the singaporebikes forum, a few experienced riders recommended to change the clutch. I went to Tai Hin to get it changed, the man whom seemed like the owner or manager said SYM original seemed to "jump" after fitting it in, he recommended to use KYMCO's clutch. Well... Anything he says, I'm just riding it for experience.
I still feel I need to clean my carburettor, the old uncle say to do that, he will need to dismantle a few parts, quite big job he said. Maybe next time then I do lar... zzz