If you have MS Office, and the PDFs don't contain any really funky formatting, copy the info out of each PDF and paste it all into a single Word document. Fix the formatting as required. Save the Word doc as a PDF. Done.
1979 KZ400 Gifted to a couple of nephews
1967 Yamaha YCS1 Bonanza
1981 Yamaha XT250H
1981 KZ440 LTD project bike
2013 Yamaha FZ6R