This might help.
For Honda Decoding:
http://atcvin.webs.com/
This website at the link above will decode all Honda ATC frame serial #s, including pre 1980 ones that are a little tricky. These can be found on the steering neck portion of the frame, behind where the headlight is on all Hondas, and most other makes.
For Other Makes:
http://decodemyvin.webs.com/
This site will decode all 1980+ frame serial/vin #s belonging to Yamaha, Kawasaki, Suzuki machines.