Motorcycle Repair: gas mileage, honda shadow ace, gas mileage

Question
I have a 1995 honda shadow ace 1100.  i recently had a decrease in gas mileage.  The bike was due for its 12000 mile service so it was done (air filter cleaned and spark plugs replaced, fuel filter was fine).  the gas mileage is still bad.  I am getting about 33 mpg at best.  It does worse on the interstate (80-85 mpg), but even riding at 60-65 mpg it is still not good.  When I first got the bike, i would average on the interstate about 40 mpg.  It has only been within the last 6 fill ups that this drop has occurred.  Not only that, my main tank goes into reserve at 3 gallons!  The owners manual says i have four gallon tank with a .5 gallon reserve.

Please help.  My car gets better gas mileage!

Answer
Sorry, Joe my experience is in pre-82 Hondas so I can't give you a specific answer.  My VF1100S gets about 40-45 depending how I drive so I agree you have something going on.  The only thing I can think of that would explain the sudden drop is a problem with the carbs that allows a lot more fuel into the engine than it's supposed to get. For instance, if the the choke linkage or cable was holding the choke on even when the lever is in the off position. I've seen this happen when the cable was kinked or rusted.  The other option would be a spark timing problem.  A ignition problem should show up as poor performance too.  Since you didn't mention a performance problem, I'm betting there's a carburation problem.  

I once had a customer bring in his bike for a similar problem.  I had tuned it up and he brought it back saying it was running like crap and got terrible mileage.  I went through it all again and rode it for a while and everything seemed fine.  Again, he brought it back with the same complaint.   I told him I'd go through it again but it all seemed fine when I rode it.  He decided to leave it and just as he was leaving, I saw him lift the seat and take out his riding gloves.  Turns out the gloves were covering up the air inlet and making the bike run rich.  You don't have anything like this going on do you?

Rich