You will need a gasket in between the carb boot and the reed cage and the reed cage and cylinder. You could have done a precise job and not damaged the sealing ring on the carb boot, in my experience thats doubtful, go with the gasket. I just purchased two vforce kx500 reed cages and they came with 2 gaskets. Is your cage for a 250? they require no trimming. the cages will fit into either bike, the 250 has a smaller inlet opening than the 500 cage. I've used both, either works fine.