@TS, i m not sifu but i hope can help u
u can do it yourself and very simple. do u know wat is distributor. there is a nut which lock the distributor and after loosen the nut u can align the distributor. align until u get ur engine smooth i.e. not so low rpm and not so high rpm when idle.
i m driving a kancil 660 and this technique is my experienced sifu told me 1