Here is a link to a DIY Carb Sync Tool: cost is around $2-$5:
http://www.powerchutes.com/manometer.aspHave not made one yet, but planning to give it a try possibly next year (both bikes have been sync'ed within the past year, so have not had an opportunity/need yet. Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII