Motorcycle Repair: poor fuel mileage, v65 magna, poor mileage

Question
I have an 86 V65 magna with 86000km and my fuel mileage has dropped about 40 kilometers per tank in the past 2 years.  I've had the valves done and carbs resinc'd. where do I start to get my fuel mileage back.  

Answer
Wow Steve, that's really bad mileage.  Forty km/tank or per gallon? Well, it has to be running really rich.  I'm assuming there's black smoke pouring out of the exhaust pipes? Is the bike running okay but just poor mileage or has the performance dropped off considerably too?  I'd start by checking the choke cable to make sure it's not holding the chokes open.  Also I've seen where mice had build nests in the air filter box causing this type of a drop in mileage.  If it's not the carbs it has to be the compression leak causing a lot of blowby out of the breather or ignition timing causing the timing to be off.  When you push the bike to move it around, is it a little more difficult than normal? Lift the front wheel off the ground and spin the front wheel.  If it drags a lot, the front brakes need rebuilding.  Do the same for the rear wheel.  

Regards
Rich