maybe it is compression (try changing your head gasket and base gasket)
it could be the condensor (in the stator plate) but is unlikely.
Venting- there are vents in your gas cap that allow the gas to flow easily down into your petcock. If they are blocked gas wont flow. (kind of like when you are poring the gas from a plastic gas can. If your dont unplug the little vent on the top gas doesnt flow out easily)
Next time it runs badly try removing the gas cap and ride. if it runs better you know whats wrong.