The 2003-2007 Honda Ruckus NPS50 service manual can be downloaded below:
Honda Ruckus NPS50 (26 megs)http://www.hondaspree.net/other/Honda_N ... Manual.pdf
File is 26 megs, so plan on a few hours across a phone modem.
You will probably want to right click on the above link, and choose "Save Target As..." rather than letting your browser open it up as a PDF. Esp. those with modems!
These are a 4-stroke 50cc bike, but still a Honda. Thanks to 66Six for bringing this to us!
Buy new air filters and gasket kits here: http://stores.ebay.com/noiseguysstore