I acquired a Vespa Grande a few weeks back, and have been struggling to get it to fire ever since. I have rebuilt the carb twice now, and cleaned it so well I can see my reflection in every part of it, however it still refuses to spray fuel. I must have turned the engine over at least 1000 times now, and not one single fire, I have spark, but never see any indication of fuel entering the cylinder. Plug is dry upon removal, never smell fuel, don't see fuel out the plug hole or the carb intake when filter/plug is removed. The bowl is filled every-time I have removed the carb, I am totally at a loss, any suggestions?