A lot of effort by many people has gone into creating the pdf's on the site to assist 650 owners.
Unfortunately there has been a lot of "leaching" of the pdf's which has been using a large volume of bandwidth.
It seems much of the leeching has been from automated systems and one system in particular rather than people legitimately posting links to files on forum pages and so changes have been made to limit direct linking to the pdf's to the legitimate forums discussing motorcycling or the 650 models
If you are unable to link to a pdf from your forum let me know and I will consider allowing direct link access.
The file you are looking for is likely to be a file on one of the pages listed below.
If the file you were attempting to link to is not one of those listed above it should be on the relevant page in the sections in the menu on the left, if not let me know, I will look into it and work out the problem.