If your bike is not singing as sweetly as it once did, have you thought about a complete carburettor overhaul. The Ring shown in the image, is just one item of a few you may require to return to smooth running and one prod starting.
All of the carburettor service items can be found on our online schematic for your model. Check the schematic for your model (where available) and take better informed decision when placing your order. Rare item - don't miss out.