Woodduck,
Go to the following link and you will find an excellent guide to tuning a recurve or longbow.
http://www.bowmaker.net/index2.htm
When you get to the webpage, look at the links at the top of the page. If you look closely you will see that there is a second row of links that are not completely visible, at least not on my monitor. Click on the far left link on the bottom row and it will take you to the Tuning Bows page..
Bill