2005 Yamaha Road Star Silverado exploded view of carburetor

SOURCE: 2005 650 V star won't idle

i would say its either drawing air or the carbs need setup. You have to check the breather pipes and the rubber manifolds for cracks or splits.
if carbs need setup, then its best taking it to a good garage, to have them balanced and adjusted.

TL

SOURCE: fuel overflow problem with 2007 roadstar silverado

Gas running out of the carb indicates that the internal float valve is not shutting off the flow when the float bowl fills up. Might need cleaned; might need a new float valve assembly. Not cranking is an electrical problem. If you mean that the engine cranks over but doesn't start - then this could be a related carb problem. Take the bike to a reputable repair center near you.

SOURCE: Yamaha V-Star 1100 backfires and will not run without choke on

Here are two solutions for you:
A - Take the carberator off and soak it in some good quality carb cleaner for about 1/2 an hour.  That should take care of any residue in the carbs.
B - Alternatively (and for the less technical minded) there is a great product called Sea Foam.  Try to find it at your local CSK auto/NAPA/Wal-Mart.  Pour a small amount (maybe 1/4 ounce) into each cylinder chamber (take out the spark plugs), try to pour a small amount into the carbs (a turkey baster works great for this), and pour the rest into the gas tank.  Let it sit for 5-10 minutes, then start it up.  *NOTE - the bike will start VERY hard at first until it burns through what's in the cylinders.  ALSO the fumes will be EXTREMELY strong and suffocating - make sure you do this OUTDOORS preferably, or at least in a VERY well ventilated area.
Good luck - I know how frustrating these things can be! :)
P.S. - I am a proud owner of a V-Star 1300 - great bikes! :)

SOURCE: how to adjust 2007 yamaha roadstar 1700 carberator

The most common adjustment would be to adjust your idle mixture screw. These guys make the job very easy with a thumbscrew to do the job. Tell them I sent you and that you need carb help. http://www.maxairengineering.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=MPS-PRO-RDSTR&Category_Code=ROADSTAR&Product_Count=3

They are great guys and very helpful. They have my bike running the best it ever has.

SOURCE: recommended fuel octane for 2005 yamaha 1100

Definitly Premium. Do not use any Ethanol blend fuels.