No distributor, only current coil.. these are single piston bikes bhai
And forget the knocking.. these are our 1970's bikes with F u c kin low quality engine oils in them! Nothing strange! Buy a CG125, try to pull it on 2nd gear from low speed and you will come to know what knocking really is!!
cd70 ko kuch nahi hota, chalta hai! In winters it happens... stable idling is always an issue with motorbikes! When cold these dont idle properly... Check for knocking when engine is fully warm, if it still knocks then get its tappets adjusted.