fuel tap will allow you to shut down the engine if it decides it wants to run away. there's nothing worse than a broken governor or injection pump which won't allow your engine to stop. it's nice to have an alternative shutoff for the fuel.
It was for the petrol model. I've long since sold the Hatz bike but there was a return on it. Never thought it was too well thought out on the Chanwood bikes though - always had trouble with leaks & air getting sucked into the system.
Stuart. M1030M1, Honda NC700S, Grom!, Toyota Corolla 1.4 Turbo Diesel. Favouring MPG over MPH.