Spud Tubes
Spud tubing requires the replacement of the main jet and emulsion tube with a combined pipe connection and jet called a spud. The main jet and emulsion tube are removed altogether and the spud screwed in their place. This renders the carburetor unsuitable for petrol operation but it is much simpler to fit than the collar method and requires no modifications of the frame and studs and no awkwardness when accessing the air filter.