"pssst, pssst" like nosie coming from carbs?

[DOGDOC97]

so I posted that the 2002 1200s that never got ridden is running after a clean out etc, I did not do antthing to the carbs, on warm up with about 1/3 choke on I get this Pssst like nosie, like maybe air is escaping or something, any ideas? It runs fine and it seems to go away once warmed up; wondering if it still has some carbon or varnsih buildup...dogdoc

[rider123]

From your first post:

My reply:

That little puffs sound under the bike when its cold is the bike running a bit lean when warming up and backfireing back through the carbs. Nothing to worry about as these bikes are jetted horibbly lean when stock. Enriching up the mixture screws a 1/4 turn may help a bit. As far as idle adjustment is concerned wait until the bike is fully warmed up to adjust it. There is no point in adjusting it when its cold as its going to rise as the bike warms up. If you are running it when cold, just hold the throttle a little bit when stopped until the bike warms up and it will start to idle on its own. Hell I have a holeshot jet kit and it still needs a bit of choke even on a warm day when absolutly cold to start. I would go on a long highway ride to see if that clears up. You could also do an "Italian tune up" (old Dell'orto carb trick). Where you take out the document tray so you have access to the velocity stack in the airbox. You rev up the bike to around 5000 or 6000 (dont redline it!) then let off the throttle while simultaniously putting your hand over the velocity stack(the rubber intake tube) this creates a shitload of vaccuum that will suck up any crap in the carbs and should clear it out a bit. Do it a couple of times.

[PaulVS]

Sounds like it could be a vacuum leak.  Check all the hoses as well as the carb sync nipples (hard to see them) on top of the carbs.