Good PDF from CCW
https://docs.google.com/file/d/0ByFv.../edit?hl=en_US

General topic on valve adjusting is here.
http://www.mychinamoto.com/forums/showthread.php?376-QingQi-%28Qlink%29-200GY-Illustrated-Valve-Adjustment&highlight=adjusting+valves

Video for Heist valve adjustment which has almost the same engine as the DF .
http://www.youtube.com/watch?v=mbJPIQQDsSM

Also look at videos for CG Honda 125 valve adjustment.