What is your jetting? What does the piston wash and plug colour look like? Bogging and poor fuel consumption is not caused by the TSS (Throttle Safety Switch, which includes the magnet switches on the carbs). Overly rich jetting will cause the problems you are experiencing and the spark plugs and piston wash will tell you the state of your carb tuning. These engines are hard on fuel, even when they are well tuned.