I think I have an excesice fuel consumption. Well, maybe not and the problem is another. The thing is that the normal fuel on position end at 80 km from full ˇand thank is medium!There is no vent holes in the lock tank cap or tank itself. Maybe a vacuum?Another history: yesterday a tunning the carburator mix in low iddle, turning the air screw and throttle screw trying to find a right constant smooth sound. I loose the felliing ::)and cause (I think so) a too rich mixture, causing blue pipe in the union zone pipe w/ exhuast (explosion gases before exahust exits?). I need some theaching words!Anyway, and for all those things (the spark is velvet black) maybe I have too a advanced timming? Help!