help

Hey im new here and just bought my first bike, its an 1977 xs650 and its got a knocking sound. The seller said it needed a valve adjustment, that didnt seem to work so I adjusted the cam. The sound is basically gone but now the bike idles at 2k and the smokes coming out the exhaust. Any ideas?

I just bought it. Its a kickstart and its a custom hard tail. Cleaned carbs cleaned jets finally got it to a good idle changed both spark plugs also. It idles fine now but everytime i go to give it gas it sputters and backfires and such. I cant find a mark of what carbs it has but i think they...