Am going to follow this tutorial with great interest. I have a bunch of old classic bikes eg Moto Guzzi V8, Manx Nortons, Bennellies and at least one AJS 7R.
That little pipe is to be cut from the length of 0.6mm SS tubing that comes with the PE set that is for the cylinder block and chain.
I'm building 2 of these kits at the moment.......1 strictly OOB and the other c/w all available PE sets. I intend to leave the PE one essentially unpainted to illustrate the amount of work that is involved. Otherwise when you paint up the PE it just looks like PLASTIC.
CORRECTION:- The information in the first sentence is not correct. The little pipe is actually in one of the plastic bags. I checked last night for this.
SORRY about that.