Any ideas on how sand can continually get into the bowl of the carb? The filter has no tears, the intake boots are are good and there is no sand in tanks. Can the carb create a vacuum effect when the bike is running? Problem I am having is the bike will pop at idle and when you crack the throttle, then it will run badly until you get mid range in the RPM's. I'll be riding the bike and it will run good up top then when I let off the throttle the bike dies out. Anyone have any ideas on what this could be? I have changed almost all the gaskets and grommets in the carb, so I'm at a loss here. Any help would be appreciated.