I have a really nice Exciter I picked up last year with only 4000miles. There has been 2 times now where it uses an unbelievable amount of gas. 8a gallons went in 50 miles. I had filled up before that and put in 3 galllons and went 32 miles. I have gone through the carbs, new yamaha needle/seats, checked float bowl levels. I did jet down 2 sizes and runs great.... spark plugs are nice brown color. I don't see or smell any gas so it is not leaking out. What in the world could be the problem? I put a nice single ply track under it as well and that turns great. My dad mentioned on his arctic cat that the vent tube in the tank was plugged and it used a pile of fuel. I would greatly appreciate any help on this. I don't know where to look next. Thank you!!