Your clutch needs greasing there are three places.
1 where small sprocket which houses the pin and ball bearing live.
2 Under the carb is a bolt that holds the end of the clutch cable, main clutch spring.
3 On the right side under the clutch , and dont forget the bean sized blob on the grars.
Read this not for the adjustment but for information http://motorbicycling.com/f4/bicycle-engine-clutch-222.html