pilot jets/pilot circuits are plugged like already said. simply take the carbs off the sled and take pilot jets and fuel screws out. make sure you get that spring, washer, and o-ring out of the fuel screw hole. then take carb cleaner and blow thru the jets and in the carbs, where the jets thread into and where the fuel screw threads into. then take the air compressor and blow thru the jets and carbs good. put back together and whalla. just make sure to check the number of turns to closed that the fuel screws are set at, and return screws to that same position. good luck.