Generally

Cam chain for the cam drive, i.e. just the chain without drive.

Tip!

Also check the condition of the crankshaft gear and cam gear, are they also bad? Then it is cheapest to buy a complete cam drive.
Cam drive engagement: There is a punched mark or dot on both the cam and the crankshaft gear. Assemble the punched dots closest to each other in a vertical line. Check using a string with a weight on one end, hold the string in front of the cam drive then it's easier to see if the engagement is correct