two of my buddies had the same problem!! the were getting some rust build up in the carb when it sat for a month or so.dealer wouldn't warranty,but did admit the were having some issues with that happening!!since then they replaced some inside parts of the carb with stainless steel ones,not sure what parts, could find out tommorow.so far good.about $35 to fix

 

Ya if could find out that be great.. and im guessing its something along that line, and it being two degrees outside that isnt helping too much..im trying for bout two more days and to the shop it goes for major redoing..no more snorkel, new axle, new cv boot, upgraded and jetted carb, stock snorkel put back on, and hopefully a good wash...i loved the idea of making it a sweet machine at first but now it just hasnt been worth it...keep feeding ideas and hopefully sooner or later ill let you guys know what the problem was

 

changed the needle and seat over to stainless steel,seems to have solved the issue!!!$35 FOR THE PARTS,they had the same problem you have!!hope this helps!!