I have no history on this bike, unfortunately, but it’s getting about half of the fuel mileage that I see reported by others.

Bike starts and idles well, and accelerates pretty much as I’d expect, though I have no frame of reference for the acceleration as I’ve never ridden a similar bike. For the same reason, I can’t say whether it’s running “smoothly” or not. (I read somewhere that if the valves are way out of adjustment, fuel economy could be affected.) I’m not riding at consistently high RPM, but do goose it occasionally.

Air filter is clean. Spark plugs look good. Choke lever moves freely and choke seems to be working correctly – ie. on a cold start, the idle speed decreases as the choke is reduced.

I can’t see any fuel coming out the exhaust and I can’t see any fuel leaks (though I realize that if it’s leaking on a hot engine there might not be much to see. ) Also, I have yet to yank the fuel tank to get a better look at the lines and intake boots on the carbs but I can't figure out how there could be a fuel leak that, seemingly, does not affect performance.

Any thoughts on what could be the problem?

Thanks in advance.

I would do the basics, tune up, valve adjustment etc. Also more info would be helpful, stock or modified intake, carb setup if intake has been modified etc. Avoid using the throttle when starting and keep the RPM's up! These are a high revving motor and love it. Mileage is going to depend on conditions and your right wrist. I would go to reserve normally at around 130 miles and look for gas. And no more than 87 octane.  Here is a link to the wKB , our 1100 "Bible".   V-Star 1100 Wiki Knowledge Base (google.com)

Problem solved and I'm feeling stupid and embarrassed. 

Here in Canada, I assume that odometers are measuring kilometres.  Bad assumption on my part.   The odo is measuring miles, so I'm getting about 40 miles to a U.S. gallon. 

I apologize for wasting your time.

Dude, thanks for the update. I was noodling away on what could cause a drastic cut in gas mileage without making the bike almost unrideable. Glad it's an easy "fix"

"Glad it's an easy "fix" "

LOL.  Inexpensive, too.  All it cost me is some humiliation. 

I would read thru the link I provided, especially the new owners section and still do the basics not knowing any history. Glad you figured it out and keep the rev's up!

That WIKI knowledge base looks like a valuable resource.

Cheers!

We have been compiling it since the 1100 came out. No doubt the go to for info.