The metal that these two parts are made of, doesn't help the situation either .
Seems like it's ' pot metal ', I know it files down easily to clean up the teeth on the cam gear .
A little tip, if you replace the cam gear and the throttle tube, if they are the original parts that the bike came with from the factory, you also need to replace the cover as well .
The hole in the cam gear, that's the part with the chain on it, is about 2-3 times the size of the original .