Ok guys, I have an impossible idle issue that is making me tear my hair out.  I'm going to replace all the vacuum lines on the engine.   What sizes am I going to need?  I can't seem to find any info online or in the Clymers (I looked, but I have an ability to over look pertinent information)

Pls halp!

Anyhow, I know a lot of it is the same size, just going to order 6 ft of each size, just need to know what they are!

THANKS!!!!

- Brendan

Have you checked the o ring under the caps of the carbs? 
That one is a bugger for idle issues.

Care to elaborate?  I'm about to set the bike on fire...

when you take off the slider cover from the top of the carry theres a small o-ring that sits under the vacuum port used to balance the carbs.  When it becomes perished or when someone takes the cover off its easy to lose and idling issues are commonplace. 

You get the o rings with a carb rebuild kit but theres probably a stock o ring size available if you didn't want to buy a kit.
check the carb rebuild videos because people do mention the o ring.  Theres also one where the carb boots cause idle issues too but its the long one (goes for about an hour on YouTube), id post a link but I'm at work and its blocked.

Hope its mildly helpful, theres not too many vacuum lines on the bike.

the main line i'd replace would be the one that goes from the carb to the frame petcock as the vacuum opens the petcock to supply fuel to the carbs (I think) if you have poor vacuum from a leak then you will have weaker fuel flow and funny idling (if its low) I'm presuming you've got a can of aerostat or similar with the bike running to check for leaks (spray and listen for revs)

http://gstwins.com/gsboard/index.php?topic=56601.msg640681#msg640681